<?xml version="1.0" encoding="us-ascii"?>
<!-- Created by Merrill Corporation -->
<!-- Generated by Fujitsu Interstage XWand B0189 -->
<!--Generated by IRIS XBRL Generation Engine-->
<link:linkbase xsi:schemaLocation="http://www.xbrl.org/2003/linkbase http://www.xbrl.org/2003/xbrl-linkbase-2003-12-31.xsd" xmlns:link="http://www.xbrl.org/2003/linkbase" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:xbrli="http://www.xbrl.org/2003/instance">
  <link:roleRef roleURI="http://www.markwest.com/role/StatementOfIncome" xlink:type="simple" xlink:href="mwe-20140630.xsd#StatementOfIncome" />
  <link:roleRef roleURI="http://www.markwest.com/role/CashFlows" xlink:type="simple" xlink:href="mwe-20140630.xsd#CashFlows" />
  <link:roleRef roleURI="http://www.markwest.com/role/DisclosureSegmentInformationDetails3" xlink:type="simple" xlink:href="mwe-20140630.xsd#DisclosureSegmentInformationDetails3" />
  <link:roleRef roleURI="http://www.markwest.com/role/DisclosureIncomeTaxesDetails" xlink:type="simple" xlink:href="mwe-20140630.xsd#DisclosureIncomeTaxesDetails" />
  <link:roleRef roleURI="http://www.markwest.com/role/DisclosureInventoriesDetails" xlink:type="simple" xlink:href="mwe-20140630.xsd#DisclosureInventoriesDetails" />
  <link:roleRef roleURI="http://www.markwest.com/role/DisclosureEarningsLossPerCommonUnitDetails" xlink:type="simple" xlink:href="mwe-20140630.xsd#DisclosureEarningsLossPerCommonUnitDetails" />
  <link:roleRef roleURI="http://www.markwest.com/role/DisclosureDerivativeFinancialInstrumentsDetails3" xlink:type="simple" xlink:href="mwe-20140630.xsd#DisclosureDerivativeFinancialInstrumentsDetails3" />
  <link:roleRef roleURI="http://www.markwest.com/role/BalanceSheet" xlink:type="simple" xlink:href="mwe-20140630.xsd#BalanceSheet" />
  <link:roleRef roleURI="http://www.markwest.com/role/DisclosureSupplementalCondensedConsolidatingFinancialInformationDetails" xlink:type="simple" xlink:href="mwe-20140630.xsd#DisclosureSupplementalCondensedConsolidatingFinancialInformationDetails" />
  <link:roleRef roleURI="http://www.markwest.com/role/DisclosureDerivativeFinancialInstrumentsDetails" xlink:type="simple" xlink:href="mwe-20140630.xsd#DisclosureDerivativeFinancialInstrumentsDetails" />
  <link:roleRef roleURI="http://www.markwest.com/role/DisclosureSegmentInformationDetails" xlink:type="simple" xlink:href="mwe-20140630.xsd#DisclosureSegmentInformationDetails" />
  <link:roleRef roleURI="http://www.markwest.com/role/DisclosureSupplementalCondensedConsolidatingFinancialInformationDetails2" xlink:type="simple" xlink:href="mwe-20140630.xsd#DisclosureSupplementalCondensedConsolidatingFinancialInformationDetails2" />
  <link:roleRef roleURI="http://www.markwest.com/role/DisclosureSupplementalCondensedConsolidatingFinancialInformationDetails3" xlink:type="simple" xlink:href="mwe-20140630.xsd#DisclosureSupplementalCondensedConsolidatingFinancialInformationDetails3" />
  <link:roleRef roleURI="http://www.markwest.com/role/DisclosureSegmentInformationDetails5" xlink:type="simple" xlink:href="mwe-20140630.xsd#DisclosureSegmentInformationDetails5" />
  <link:roleRef roleURI="http://www.markwest.com/role/DisclosureSegmentInformationDetails2" xlink:type="simple" xlink:href="mwe-20140630.xsd#DisclosureSegmentInformationDetails2" />
  <link:roleRef roleURI="http://www.markwest.com/role/DisclosureDerivativeFinancialInstrumentsDetails4" xlink:type="simple" xlink:href="mwe-20140630.xsd#DisclosureDerivativeFinancialInstrumentsDetails4" />
  <link:roleRef roleURI="http://www.markwest.com/role/DisclosureBusinessCombinationsDetails" xlink:type="simple" xlink:href="mwe-20140630.xsd#DisclosureBusinessCombinationsDetails" />
  <link:calculationLink xlink:type="extended" xlink:role="http://www.markwest.com/role/StatementOfIncome">
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_NetIncomeLoss" xlink:label="us-gaap_NetIncomeLoss" xlink:title="NetIncomeLoss" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ProfitLoss" xlink:label="us-gaap_ProfitLoss" xlink:title="ProfitLoss" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_NetIncomeLoss" xlink:to="us-gaap_ProfitLoss" xlink:title="calculation: us-gaap_NetIncomeLoss to us-gaap_ProfitLoss" use="optional" order="1.0" weight="1" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest" xlink:label="us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest" xlink:title="IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_ProfitLoss" xlink:to="us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest" xlink:title="calculation: us-gaap_ProfitLoss to us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest" order="1.0" weight="1" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_OperatingIncomeLoss" xlink:label="us-gaap_OperatingIncomeLoss" xlink:title="OperatingIncomeLoss" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest" xlink:to="us-gaap_OperatingIncomeLoss" xlink:title="calculation: us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest to us-gaap_OperatingIncomeLoss" use="optional" order="1.0" weight="1" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_Revenues" xlink:label="us-gaap_Revenues" xlink:title="Revenues" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_OperatingIncomeLoss" xlink:to="us-gaap_Revenues" xlink:title="calculation: us-gaap_OperatingIncomeLoss to us-gaap_Revenues" order="1.0" weight="1" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_CostsAndExpenses" xlink:label="us-gaap_CostsAndExpenses" xlink:title="CostsAndExpenses" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_OperatingIncomeLoss" xlink:to="us-gaap_CostsAndExpenses" xlink:title="calculation: us-gaap_OperatingIncomeLoss to us-gaap_CostsAndExpenses" order="2.0" weight="-1" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_NaturalGasMidstreamCosts" xlink:label="us-gaap_NaturalGasMidstreamCosts" xlink:title="NaturalGasMidstreamCosts" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_CostsAndExpenses" xlink:to="us-gaap_NaturalGasMidstreamCosts" xlink:title="calculation: us-gaap_CostsAndExpenses to us-gaap_NaturalGasMidstreamCosts" use="optional" order="1.0" weight="1" />
    <link:loc xlink:type="locator" xlink:href="mwe-20140630.xsd#mwe_GainLossOnPriceRiskDerivativeInstrumentsNotDesignatedAsHedgingInstrumentsRelatedToProductCost" xlink:label="mwe_GainLossOnPriceRiskDerivativeInstrumentsNotDesignatedAsHedgingInstrumentsRelatedToProductCost" xlink:title="GainLossOnPriceRiskDerivativeInstrumentsNotDesignatedAsHedgingInstrumentsRelatedToProductCost" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_CostsAndExpenses" xlink:to="mwe_GainLossOnPriceRiskDerivativeInstrumentsNotDesignatedAsHedgingInstrumentsRelatedToProductCost" xlink:title="calculation: us-gaap_CostsAndExpenses to mwe_GainLossOnPriceRiskDerivativeInstrumentsNotDesignatedAsHedgingInstrumentsRelatedToProductCost" use="optional" order="2.0" weight="-1" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_FacilityCosts" xlink:label="us-gaap_FacilityCosts" xlink:title="FacilityCosts" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_CostsAndExpenses" xlink:to="us-gaap_FacilityCosts" xlink:title="calculation: us-gaap_CostsAndExpenses to us-gaap_FacilityCosts" use="optional" order="3.0" weight="1" />
    <link:loc xlink:type="locator" xlink:href="mwe-20140630.xsd#mwe_GainLossOnPriceRiskDerivativeInstrumentsNotDesignatedAsHedgingInstrumentsRelatedToFacilityExpense" xlink:label="mwe_GainLossOnPriceRiskDerivativeInstrumentsNotDesignatedAsHedgingInstrumentsRelatedToFacilityExpense" xlink:title="GainLossOnPriceRiskDerivativeInstrumentsNotDesignatedAsHedgingInstrumentsRelatedToFacilityExpense" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_CostsAndExpenses" xlink:to="mwe_GainLossOnPriceRiskDerivativeInstrumentsNotDesignatedAsHedgingInstrumentsRelatedToFacilityExpense" xlink:title="calculation: us-gaap_CostsAndExpenses to mwe_GainLossOnPriceRiskDerivativeInstrumentsNotDesignatedAsHedgingInstrumentsRelatedToFacilityExpense" use="optional" order="4.0" weight="-1" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_SellingGeneralAndAdministrativeExpense" xlink:label="us-gaap_SellingGeneralAndAdministrativeExpense" xlink:title="SellingGeneralAndAdministrativeExpense" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_CostsAndExpenses" xlink:to="us-gaap_SellingGeneralAndAdministrativeExpense" xlink:title="calculation: us-gaap_CostsAndExpenses to us-gaap_SellingGeneralAndAdministrativeExpense" use="optional" order="5.0" weight="1" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_Depreciation" xlink:label="us-gaap_Depreciation" xlink:title="Depreciation" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_CostsAndExpenses" xlink:to="us-gaap_Depreciation" xlink:title="calculation: us-gaap_CostsAndExpenses to us-gaap_Depreciation" use="optional" order="6.0" weight="1" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_AmortizationOfIntangibleAssets" xlink:label="us-gaap_AmortizationOfIntangibleAssets" xlink:title="AmortizationOfIntangibleAssets" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_CostsAndExpenses" xlink:to="us-gaap_AmortizationOfIntangibleAssets" xlink:title="calculation: us-gaap_CostsAndExpenses to us-gaap_AmortizationOfIntangibleAssets" use="optional" order="7.0" weight="1" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_GainLossOnDispositionOfAssets" xlink:label="us-gaap_GainLossOnDispositionOfAssets" xlink:title="GainLossOnDispositionOfAssets" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_CostsAndExpenses" xlink:to="us-gaap_GainLossOnDispositionOfAssets" xlink:title="calculation: us-gaap_CostsAndExpenses to us-gaap_GainLossOnDispositionOfAssets" use="optional" order="8.0" weight="-1" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_AssetRetirementObligationAccretionExpense" xlink:label="us-gaap_AssetRetirementObligationAccretionExpense" xlink:title="AssetRetirementObligationAccretionExpense" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_CostsAndExpenses" xlink:to="us-gaap_AssetRetirementObligationAccretionExpense" xlink:title="calculation: us-gaap_CostsAndExpenses to us-gaap_AssetRetirementObligationAccretionExpense" use="optional" order="9.0" weight="1" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_IncomeLossFromEquityMethodInvestments" xlink:label="us-gaap_IncomeLossFromEquityMethodInvestments" xlink:title="IncomeLossFromEquityMethodInvestments" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest" xlink:to="us-gaap_IncomeLossFromEquityMethodInvestments" xlink:title="calculation: us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest to us-gaap_IncomeLossFromEquityMethodInvestments" use="optional" order="2.0" weight="1" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_InvestmentIncomeInterest" xlink:label="us-gaap_InvestmentIncomeInterest" xlink:title="InvestmentIncomeInterest" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest" xlink:to="us-gaap_InvestmentIncomeInterest" xlink:title="calculation: us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest to us-gaap_InvestmentIncomeInterest" use="optional" order="3.0" weight="1" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_InterestExpense" xlink:label="us-gaap_InterestExpense" xlink:title="InterestExpense" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest" xlink:to="us-gaap_InterestExpense" xlink:title="calculation: us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest to us-gaap_InterestExpense" use="optional" order="4.0" weight="-1" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_AmortizationOfFinancingCostsAndDiscounts" xlink:label="us-gaap_AmortizationOfFinancingCostsAndDiscounts" xlink:title="AmortizationOfFinancingCostsAndDiscounts" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest" xlink:to="us-gaap_AmortizationOfFinancingCostsAndDiscounts" xlink:title="calculation: us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest to us-gaap_AmortizationOfFinancingCostsAndDiscounts" use="optional" order="5.0" weight="-1" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_GainsLossesOnExtinguishmentOfDebt" xlink:label="us-gaap_GainsLossesOnExtinguishmentOfDebt" xlink:title="GainsLossesOnExtinguishmentOfDebt" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest" xlink:to="us-gaap_GainsLossesOnExtinguishmentOfDebt" xlink:title="calculation: us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest to us-gaap_GainsLossesOnExtinguishmentOfDebt" use="optional" order="6.0" weight="1" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_OtherNonoperatingIncomeExpense" xlink:label="us-gaap_OtherNonoperatingIncomeExpense" xlink:title="OtherNonoperatingIncomeExpense" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest" xlink:to="us-gaap_OtherNonoperatingIncomeExpense" xlink:title="calculation: us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest to us-gaap_OtherNonoperatingIncomeExpense" use="optional" order="7.0" weight="1" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_IncomeTaxExpenseBenefit" xlink:label="us-gaap_IncomeTaxExpenseBenefit" xlink:title="IncomeTaxExpenseBenefit" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_ProfitLoss" xlink:to="us-gaap_IncomeTaxExpenseBenefit" xlink:title="calculation: us-gaap_ProfitLoss to us-gaap_IncomeTaxExpenseBenefit" use="optional" order="2.0" weight="-1" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_CurrentIncomeTaxExpenseBenefit" xlink:label="us-gaap_CurrentIncomeTaxExpenseBenefit" xlink:title="CurrentIncomeTaxExpenseBenefit" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_IncomeTaxExpenseBenefit" xlink:to="us-gaap_CurrentIncomeTaxExpenseBenefit" xlink:title="calculation: us-gaap_IncomeTaxExpenseBenefit to us-gaap_CurrentIncomeTaxExpenseBenefit" order="1.0" weight="1" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_DeferredIncomeTaxExpenseBenefit" xlink:label="us-gaap_DeferredIncomeTaxExpenseBenefit" xlink:title="DeferredIncomeTaxExpenseBenefit" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_IncomeTaxExpenseBenefit" xlink:to="us-gaap_DeferredIncomeTaxExpenseBenefit" xlink:title="calculation: us-gaap_IncomeTaxExpenseBenefit to us-gaap_DeferredIncomeTaxExpenseBenefit" order="2.0" weight="1" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_NetIncomeLossAttributableToNoncontrollingInterest" xlink:label="us-gaap_NetIncomeLossAttributableToNoncontrollingInterest" xlink:title="NetIncomeLossAttributableToNoncontrollingInterest" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_NetIncomeLoss" xlink:to="us-gaap_NetIncomeLossAttributableToNoncontrollingInterest" xlink:title="calculation: us-gaap_NetIncomeLoss to us-gaap_NetIncomeLossAttributableToNoncontrollingInterest" use="optional" order="2.0" weight="-1" />
  </link:calculationLink>
  <link:calculationLink xlink:type="extended" xlink:role="http://www.markwest.com/role/CashFlows">
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_NetCashProvidedByUsedInOperatingActivitiesContinuingOperations" xlink:label="us-gaap_NetCashProvidedByUsedInOperatingActivitiesContinuingOperations" xlink:title="NetCashProvidedByUsedInOperatingActivitiesContinuingOperations" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ProfitLoss" xlink:label="us-gaap_ProfitLoss" xlink:title="ProfitLoss" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_NetCashProvidedByUsedInOperatingActivitiesContinuingOperations" xlink:to="us-gaap_ProfitLoss" xlink:title="calculation: us-gaap_NetCashProvidedByUsedInOperatingActivitiesContinuingOperations to us-gaap_ProfitLoss" use="optional" order="1.0" weight="1" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_Depreciation" xlink:label="us-gaap_Depreciation" xlink:title="Depreciation" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_NetCashProvidedByUsedInOperatingActivitiesContinuingOperations" xlink:to="us-gaap_Depreciation" xlink:title="calculation: us-gaap_NetCashProvidedByUsedInOperatingActivitiesContinuingOperations to us-gaap_Depreciation" use="optional" order="2.0" weight="1" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_AmortizationOfIntangibleAssets" xlink:label="us-gaap_AmortizationOfIntangibleAssets" xlink:title="AmortizationOfIntangibleAssets" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_NetCashProvidedByUsedInOperatingActivitiesContinuingOperations" xlink:to="us-gaap_AmortizationOfIntangibleAssets" xlink:title="calculation: us-gaap_NetCashProvidedByUsedInOperatingActivitiesContinuingOperations to us-gaap_AmortizationOfIntangibleAssets" use="optional" order="3.0" weight="1" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_GainsLossesOnExtinguishmentOfDebt" xlink:label="us-gaap_GainsLossesOnExtinguishmentOfDebt" xlink:title="GainsLossesOnExtinguishmentOfDebt" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_NetCashProvidedByUsedInOperatingActivitiesContinuingOperations" xlink:to="us-gaap_GainsLossesOnExtinguishmentOfDebt" xlink:title="calculation: us-gaap_NetCashProvidedByUsedInOperatingActivitiesContinuingOperations to us-gaap_GainsLossesOnExtinguishmentOfDebt" use="optional" order="4.0" weight="-1" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_AmortizationOfFinancingCostsAndDiscounts" xlink:label="us-gaap_AmortizationOfFinancingCostsAndDiscounts" xlink:title="AmortizationOfFinancingCostsAndDiscounts" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_NetCashProvidedByUsedInOperatingActivitiesContinuingOperations" xlink:to="us-gaap_AmortizationOfFinancingCostsAndDiscounts" xlink:title="calculation: us-gaap_NetCashProvidedByUsedInOperatingActivitiesContinuingOperations to us-gaap_AmortizationOfFinancingCostsAndDiscounts" use="optional" order="5.0" weight="1" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_AssetRetirementObligationAccretionExpense" xlink:label="us-gaap_AssetRetirementObligationAccretionExpense" xlink:title="AssetRetirementObligationAccretionExpense" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_NetCashProvidedByUsedInOperatingActivitiesContinuingOperations" xlink:to="us-gaap_AssetRetirementObligationAccretionExpense" xlink:title="calculation: us-gaap_NetCashProvidedByUsedInOperatingActivitiesContinuingOperations to us-gaap_AssetRetirementObligationAccretionExpense" use="optional" order="6.0" weight="1" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_OtherAmortizationOfDeferredCharges" xlink:label="us-gaap_OtherAmortizationOfDeferredCharges" xlink:title="OtherAmortizationOfDeferredCharges" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_NetCashProvidedByUsedInOperatingActivitiesContinuingOperations" xlink:to="us-gaap_OtherAmortizationOfDeferredCharges" xlink:title="calculation: us-gaap_NetCashProvidedByUsedInOperatingActivitiesContinuingOperations to us-gaap_OtherAmortizationOfDeferredCharges" use="optional" order="7.0" weight="1" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ShareBasedCompensation" xlink:label="us-gaap_ShareBasedCompensation" xlink:title="ShareBasedCompensation" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_NetCashProvidedByUsedInOperatingActivitiesContinuingOperations" xlink:to="us-gaap_ShareBasedCompensation" xlink:title="calculation: us-gaap_NetCashProvidedByUsedInOperatingActivitiesContinuingOperations to us-gaap_ShareBasedCompensation" use="optional" order="8.0" weight="1" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_IncomeLossFromEquityMethodInvestments" xlink:label="us-gaap_IncomeLossFromEquityMethodInvestments" xlink:title="IncomeLossFromEquityMethodInvestments" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_NetCashProvidedByUsedInOperatingActivitiesContinuingOperations" xlink:to="us-gaap_IncomeLossFromEquityMethodInvestments" xlink:title="calculation: us-gaap_NetCashProvidedByUsedInOperatingActivitiesContinuingOperations to us-gaap_IncomeLossFromEquityMethodInvestments" use="optional" order="9.0" weight="-1" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_EquityMethodInvestmentDividendsOrDistributions" xlink:label="us-gaap_EquityMethodInvestmentDividendsOrDistributions" xlink:title="EquityMethodInvestmentDividendsOrDistributions" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_NetCashProvidedByUsedInOperatingActivitiesContinuingOperations" xlink:to="us-gaap_EquityMethodInvestmentDividendsOrDistributions" xlink:title="calculation: us-gaap_NetCashProvidedByUsedInOperatingActivitiesContinuingOperations to us-gaap_EquityMethodInvestmentDividendsOrDistributions" use="optional" order="10.0" weight="1" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_UnrealizedGainLossOnDerivatives" xlink:label="us-gaap_UnrealizedGainLossOnDerivatives" xlink:title="UnrealizedGainLossOnDerivatives" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_NetCashProvidedByUsedInOperatingActivitiesContinuingOperations" xlink:to="us-gaap_UnrealizedGainLossOnDerivatives" xlink:title="calculation: us-gaap_NetCashProvidedByUsedInOperatingActivitiesContinuingOperations to us-gaap_UnrealizedGainLossOnDerivatives" use="optional" order="11.0" weight="-1" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_GainLossOnDispositionOfAssets" xlink:label="us-gaap_GainLossOnDispositionOfAssets" xlink:title="GainLossOnDispositionOfAssets" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_NetCashProvidedByUsedInOperatingActivitiesContinuingOperations" xlink:to="us-gaap_GainLossOnDispositionOfAssets" xlink:title="calculation: us-gaap_NetCashProvidedByUsedInOperatingActivitiesContinuingOperations to us-gaap_GainLossOnDispositionOfAssets" use="optional" order="12.0" weight="-1" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_DeferredIncomeTaxExpenseBenefit" xlink:label="us-gaap_DeferredIncomeTaxExpenseBenefit" xlink:title="DeferredIncomeTaxExpenseBenefit" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_NetCashProvidedByUsedInOperatingActivitiesContinuingOperations" xlink:to="us-gaap_DeferredIncomeTaxExpenseBenefit" xlink:title="calculation: us-gaap_NetCashProvidedByUsedInOperatingActivitiesContinuingOperations to us-gaap_DeferredIncomeTaxExpenseBenefit" use="optional" order="13.0" weight="1" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_IncreaseDecreaseInReceivables" xlink:label="us-gaap_IncreaseDecreaseInReceivables" xlink:title="IncreaseDecreaseInReceivables" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_NetCashProvidedByUsedInOperatingActivitiesContinuingOperations" xlink:to="us-gaap_IncreaseDecreaseInReceivables" xlink:title="calculation: us-gaap_NetCashProvidedByUsedInOperatingActivitiesContinuingOperations to us-gaap_IncreaseDecreaseInReceivables" use="optional" order="14.0" weight="-1" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_IncreaseDecreaseInAccountsReceivableRelatedParties" xlink:label="us-gaap_IncreaseDecreaseInAccountsReceivableRelatedParties" xlink:title="IncreaseDecreaseInAccountsReceivableRelatedParties" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_NetCashProvidedByUsedInOperatingActivitiesContinuingOperations" xlink:to="us-gaap_IncreaseDecreaseInAccountsReceivableRelatedParties" xlink:title="calculation: us-gaap_NetCashProvidedByUsedInOperatingActivitiesContinuingOperations to us-gaap_IncreaseDecreaseInAccountsReceivableRelatedParties" use="optional" order="15.0" weight="-1" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_IncreaseDecreaseInInventories" xlink:label="us-gaap_IncreaseDecreaseInInventories" xlink:title="IncreaseDecreaseInInventories" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_NetCashProvidedByUsedInOperatingActivitiesContinuingOperations" xlink:to="us-gaap_IncreaseDecreaseInInventories" xlink:title="calculation: us-gaap_NetCashProvidedByUsedInOperatingActivitiesContinuingOperations to us-gaap_IncreaseDecreaseInInventories" use="optional" order="16.0" weight="-1" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_IncreaseDecreaseInOtherCurrentAssets" xlink:label="us-gaap_IncreaseDecreaseInOtherCurrentAssets" xlink:title="IncreaseDecreaseInOtherCurrentAssets" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_NetCashProvidedByUsedInOperatingActivitiesContinuingOperations" xlink:to="us-gaap_IncreaseDecreaseInOtherCurrentAssets" xlink:title="calculation: us-gaap_NetCashProvidedByUsedInOperatingActivitiesContinuingOperations to us-gaap_IncreaseDecreaseInOtherCurrentAssets" use="optional" order="17.0" weight="-1" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_IncreaseDecreaseInAccountsPayableAndAccruedLiabilities" xlink:label="us-gaap_IncreaseDecreaseInAccountsPayableAndAccruedLiabilities" xlink:title="IncreaseDecreaseInAccountsPayableAndAccruedLiabilities" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_NetCashProvidedByUsedInOperatingActivitiesContinuingOperations" xlink:to="us-gaap_IncreaseDecreaseInAccountsPayableAndAccruedLiabilities" xlink:title="calculation: us-gaap_NetCashProvidedByUsedInOperatingActivitiesContinuingOperations to us-gaap_IncreaseDecreaseInAccountsPayableAndAccruedLiabilities" use="optional" order="18.0" weight="1" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_IncreaseDecreaseInOtherOperatingAssets" xlink:label="us-gaap_IncreaseDecreaseInOtherOperatingAssets" xlink:title="IncreaseDecreaseInOtherOperatingAssets" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_NetCashProvidedByUsedInOperatingActivitiesContinuingOperations" xlink:to="us-gaap_IncreaseDecreaseInOtherOperatingAssets" xlink:title="calculation: us-gaap_NetCashProvidedByUsedInOperatingActivitiesContinuingOperations to us-gaap_IncreaseDecreaseInOtherOperatingAssets" use="optional" order="19.0" weight="-1" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_IncreaseDecreaseInOtherOperatingLiabilities" xlink:label="us-gaap_IncreaseDecreaseInOtherOperatingLiabilities" xlink:title="IncreaseDecreaseInOtherOperatingLiabilities" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_NetCashProvidedByUsedInOperatingActivitiesContinuingOperations" xlink:to="us-gaap_IncreaseDecreaseInOtherOperatingLiabilities" xlink:title="calculation: us-gaap_NetCashProvidedByUsedInOperatingActivitiesContinuingOperations to us-gaap_IncreaseDecreaseInOtherOperatingLiabilities" use="optional" order="20.0" weight="1" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_NetCashProvidedByUsedInFinancingActivitiesContinuingOperations" xlink:label="us-gaap_NetCashProvidedByUsedInFinancingActivitiesContinuingOperations" xlink:title="NetCashProvidedByUsedInFinancingActivitiesContinuingOperations" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ProceedsFromIssuanceOfCommonLimitedPartnersUnits" xlink:label="us-gaap_ProceedsFromIssuanceOfCommonLimitedPartnersUnits" xlink:title="ProceedsFromIssuanceOfCommonLimitedPartnersUnits" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_NetCashProvidedByUsedInFinancingActivitiesContinuingOperations" xlink:to="us-gaap_ProceedsFromIssuanceOfCommonLimitedPartnersUnits" xlink:title="calculation: us-gaap_NetCashProvidedByUsedInFinancingActivitiesContinuingOperations to us-gaap_ProceedsFromIssuanceOfCommonLimitedPartnersUnits" use="optional" order="1.0" weight="1" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ProceedsFromLinesOfCredit" xlink:label="us-gaap_ProceedsFromLinesOfCredit" xlink:title="ProceedsFromLinesOfCredit" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_NetCashProvidedByUsedInFinancingActivitiesContinuingOperations" xlink:to="us-gaap_ProceedsFromLinesOfCredit" xlink:title="calculation: us-gaap_NetCashProvidedByUsedInFinancingActivitiesContinuingOperations to us-gaap_ProceedsFromLinesOfCredit" use="optional" order="2.0" weight="1" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_RepaymentsOfLinesOfCredit" xlink:label="us-gaap_RepaymentsOfLinesOfCredit" xlink:title="RepaymentsOfLinesOfCredit" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_NetCashProvidedByUsedInFinancingActivitiesContinuingOperations" xlink:to="us-gaap_RepaymentsOfLinesOfCredit" xlink:title="calculation: us-gaap_NetCashProvidedByUsedInFinancingActivitiesContinuingOperations to us-gaap_RepaymentsOfLinesOfCredit" use="optional" order="3.0" weight="-1" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ProceedsFromIssuanceOfLongTermDebt" xlink:label="us-gaap_ProceedsFromIssuanceOfLongTermDebt" xlink:title="ProceedsFromIssuanceOfLongTermDebt" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_NetCashProvidedByUsedInFinancingActivitiesContinuingOperations" xlink:to="us-gaap_ProceedsFromIssuanceOfLongTermDebt" xlink:title="calculation: us-gaap_NetCashProvidedByUsedInFinancingActivitiesContinuingOperations to us-gaap_ProceedsFromIssuanceOfLongTermDebt" use="optional" order="4.0" weight="1" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_RepaymentsOfLongTermDebt" xlink:label="us-gaap_RepaymentsOfLongTermDebt" xlink:title="RepaymentsOfLongTermDebt" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_NetCashProvidedByUsedInFinancingActivitiesContinuingOperations" xlink:to="us-gaap_RepaymentsOfLongTermDebt" xlink:title="calculation: us-gaap_NetCashProvidedByUsedInFinancingActivitiesContinuingOperations to us-gaap_RepaymentsOfLongTermDebt" use="optional" order="5.0" weight="-1" />
    <link:loc xlink:type="locator" xlink:href="mwe-20140630.xsd#mwe_PaymentsOfPremiumsOnRedemptionOfLongTermDebt" xlink:label="mwe_PaymentsOfPremiumsOnRedemptionOfLongTermDebt" xlink:title="PaymentsOfPremiumsOnRedemptionOfLongTermDebt" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_NetCashProvidedByUsedInFinancingActivitiesContinuingOperations" xlink:to="mwe_PaymentsOfPremiumsOnRedemptionOfLongTermDebt" xlink:title="calculation: us-gaap_NetCashProvidedByUsedInFinancingActivitiesContinuingOperations to mwe_PaymentsOfPremiumsOnRedemptionOfLongTermDebt" use="optional" order="6.0" weight="-1" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_PaymentOfFinancingAndStockIssuanceCosts" xlink:label="us-gaap_PaymentOfFinancingAndStockIssuanceCosts" xlink:title="PaymentOfFinancingAndStockIssuanceCosts" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_NetCashProvidedByUsedInFinancingActivitiesContinuingOperations" xlink:to="us-gaap_PaymentOfFinancingAndStockIssuanceCosts" xlink:title="calculation: us-gaap_NetCashProvidedByUsedInFinancingActivitiesContinuingOperations to us-gaap_PaymentOfFinancingAndStockIssuanceCosts" use="optional" order="7.0" weight="-1" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ProceedsFromMinorityShareholders" xlink:label="us-gaap_ProceedsFromMinorityShareholders" xlink:title="ProceedsFromMinorityShareholders" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_NetCashProvidedByUsedInFinancingActivitiesContinuingOperations" xlink:to="us-gaap_ProceedsFromMinorityShareholders" xlink:title="calculation: us-gaap_NetCashProvidedByUsedInFinancingActivitiesContinuingOperations to us-gaap_ProceedsFromMinorityShareholders" use="optional" order="8.0" weight="1" />
    <link:loc xlink:type="locator" xlink:href="mwe-20140630.xsd#mwe_PaymentOfLiability" xlink:label="mwe_PaymentOfLiability" xlink:title="PaymentOfLiability" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_NetCashProvidedByUsedInFinancingActivitiesContinuingOperations" xlink:to="mwe_PaymentOfLiability" xlink:title="calculation: us-gaap_NetCashProvidedByUsedInFinancingActivitiesContinuingOperations to mwe_PaymentOfLiability" use="optional" order="9.0" weight="-1" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_PaymentsRelatedToTaxWithholdingForShareBasedCompensation" xlink:label="us-gaap_PaymentsRelatedToTaxWithholdingForShareBasedCompensation" xlink:title="PaymentsRelatedToTaxWithholdingForShareBasedCompensation" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_NetCashProvidedByUsedInFinancingActivitiesContinuingOperations" xlink:to="us-gaap_PaymentsRelatedToTaxWithholdingForShareBasedCompensation" xlink:title="calculation: us-gaap_NetCashProvidedByUsedInFinancingActivitiesContinuingOperations to us-gaap_PaymentsRelatedToTaxWithholdingForShareBasedCompensation" use="optional" order="10.0" weight="-1" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ExcessTaxBenefitFromShareBasedCompensationFinancingActivities" xlink:label="us-gaap_ExcessTaxBenefitFromShareBasedCompensationFinancingActivities" xlink:title="ExcessTaxBenefitFromShareBasedCompensationFinancingActivities" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_NetCashProvidedByUsedInFinancingActivitiesContinuingOperations" xlink:to="us-gaap_ExcessTaxBenefitFromShareBasedCompensationFinancingActivities" xlink:title="calculation: us-gaap_NetCashProvidedByUsedInFinancingActivitiesContinuingOperations to us-gaap_ExcessTaxBenefitFromShareBasedCompensationFinancingActivities" use="optional" order="11.0" weight="1" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_PaymentsOfDividendsCommonStock" xlink:label="us-gaap_PaymentsOfDividendsCommonStock" xlink:title="PaymentsOfDividendsCommonStock" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_NetCashProvidedByUsedInFinancingActivitiesContinuingOperations" xlink:to="us-gaap_PaymentsOfDividendsCommonStock" xlink:title="calculation: us-gaap_NetCashProvidedByUsedInFinancingActivitiesContinuingOperations to us-gaap_PaymentsOfDividendsCommonStock" use="optional" order="12.0" weight="-1" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_PaymentsOfDividendsMinorityInterest" xlink:label="us-gaap_PaymentsOfDividendsMinorityInterest" xlink:title="PaymentsOfDividendsMinorityInterest" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_NetCashProvidedByUsedInFinancingActivitiesContinuingOperations" xlink:to="us-gaap_PaymentsOfDividendsMinorityInterest" xlink:title="calculation: us-gaap_NetCashProvidedByUsedInFinancingActivitiesContinuingOperations to us-gaap_PaymentsOfDividendsMinorityInterest" use="optional" order="13.0" weight="-1" />
  </link:calculationLink>
  <link:calculationLink xlink:type="extended" xlink:role="http://www.markwest.com/role/DisclosureSegmentInformationDetails3">
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_OperatingIncomeLoss" xlink:label="us-gaap_OperatingIncomeLoss" xlink:title="OperatingIncomeLoss" />
    <link:loc xlink:type="locator" xlink:href="mwe-20140630.xsd#mwe_MinorityInterestInOperatingIncomeLossLimitedPartnerships" xlink:label="mwe_MinorityInterestInOperatingIncomeLossLimitedPartnerships" xlink:title="MinorityInterestInOperatingIncomeLossLimitedPartnerships" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_OperatingIncomeLoss" xlink:to="mwe_MinorityInterestInOperatingIncomeLossLimitedPartnerships" xlink:title="calculation: us-gaap_OperatingIncomeLoss to mwe_MinorityInterestInOperatingIncomeLossLimitedPartnerships" use="optional" order="1.0" weight="-1" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_DerivativeGainLossOnDerivativeNet" xlink:label="us-gaap_DerivativeGainLossOnDerivativeNet" xlink:title="DerivativeGainLossOnDerivativeNet" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_OperatingIncomeLoss" xlink:to="us-gaap_DerivativeGainLossOnDerivativeNet" xlink:title="calculation: us-gaap_OperatingIncomeLoss to us-gaap_DerivativeGainLossOnDerivativeNet" use="optional" order="2.0" weight="1" />
    <link:loc xlink:type="locator" xlink:href="mwe-20140630.xsd#mwe_RevenueAdjustmentForUnconsolidatedAffiliate" xlink:label="mwe_RevenueAdjustmentForUnconsolidatedAffiliate" xlink:title="RevenueAdjustmentForUnconsolidatedAffiliate" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_OperatingIncomeLoss" xlink:to="mwe_RevenueAdjustmentForUnconsolidatedAffiliate" xlink:title="calculation: us-gaap_OperatingIncomeLoss to mwe_RevenueAdjustmentForUnconsolidatedAffiliate" use="optional" order="3.0" weight="-1" />
    <link:loc xlink:type="locator" xlink:href="mwe-20140630.xsd#mwe_DeferredRevenueAdjustment" xlink:label="mwe_DeferredRevenueAdjustment" xlink:title="DeferredRevenueAdjustment" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_OperatingIncomeLoss" xlink:to="mwe_DeferredRevenueAdjustment" xlink:title="calculation: us-gaap_OperatingIncomeLoss to mwe_DeferredRevenueAdjustment" use="optional" order="4.0" weight="-1" />
    <link:loc xlink:type="locator" xlink:href="mwe-20140630.xsd#mwe_FacilityCostsLaborAndRelatedExpense" xlink:label="mwe_FacilityCostsLaborAndRelatedExpense" xlink:title="FacilityCostsLaborAndRelatedExpense" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_OperatingIncomeLoss" xlink:to="mwe_FacilityCostsLaborAndRelatedExpense" xlink:title="calculation: us-gaap_OperatingIncomeLoss to mwe_FacilityCostsLaborAndRelatedExpense" use="optional" order="5.0" weight="-1" />
    <link:loc xlink:type="locator" xlink:href="mwe-20140630.xsd#mwe_FacilityExpenseAndPurchaseProductCostAdjustmentsForUnconsolidatedAffiliate" xlink:label="mwe_FacilityExpenseAndPurchaseProductCostAdjustmentsForUnconsolidatedAffiliate" xlink:title="FacilityExpenseAndPurchaseProductCostAdjustmentsForUnconsolidatedAffiliate" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_OperatingIncomeLoss" xlink:to="mwe_FacilityExpenseAndPurchaseProductCostAdjustmentsForUnconsolidatedAffiliate" xlink:title="calculation: us-gaap_OperatingIncomeLoss to mwe_FacilityExpenseAndPurchaseProductCostAdjustmentsForUnconsolidatedAffiliate" use="optional" order="6.0" weight="1" />
    <link:loc xlink:type="locator" xlink:href="mwe-20140630.xsd#mwe_PortionOfOperatingIncomeLossAttributableToNoncontrollingInterestsOfUnconsolidatedAffiliate" xlink:label="mwe_PortionOfOperatingIncomeLossAttributableToNoncontrollingInterestsOfUnconsolidatedAffiliate" xlink:title="PortionOfOperatingIncomeLossAttributableToNoncontrollingInterestsOfUnconsolidatedAffiliate" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_OperatingIncomeLoss" xlink:to="mwe_PortionOfOperatingIncomeLossAttributableToNoncontrollingInterestsOfUnconsolidatedAffiliate" xlink:title="calculation: us-gaap_OperatingIncomeLoss to mwe_PortionOfOperatingIncomeLossAttributableToNoncontrollingInterestsOfUnconsolidatedAffiliate" use="optional" order="7.0" weight="1" />
    <link:loc xlink:type="locator" xlink:href="mwe-20140630.xsd#mwe_FacilityExpensesAdjustments" xlink:label="mwe_FacilityExpensesAdjustments" xlink:title="FacilityExpensesAdjustments" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_OperatingIncomeLoss" xlink:to="mwe_FacilityExpensesAdjustments" xlink:title="calculation: us-gaap_OperatingIncomeLoss to mwe_FacilityExpensesAdjustments" use="optional" order="8.0" weight="1" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_SellingGeneralAndAdministrativeExpense" xlink:label="us-gaap_SellingGeneralAndAdministrativeExpense" xlink:title="SellingGeneralAndAdministrativeExpense" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_OperatingIncomeLoss" xlink:to="us-gaap_SellingGeneralAndAdministrativeExpense" xlink:title="calculation: us-gaap_OperatingIncomeLoss to us-gaap_SellingGeneralAndAdministrativeExpense" use="optional" order="9.0" weight="-1" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_Depreciation" xlink:label="us-gaap_Depreciation" xlink:title="Depreciation" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_OperatingIncomeLoss" xlink:to="us-gaap_Depreciation" xlink:title="calculation: us-gaap_OperatingIncomeLoss to us-gaap_Depreciation" use="optional" order="10.0" weight="-1" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_AmortizationOfIntangibleAssets" xlink:label="us-gaap_AmortizationOfIntangibleAssets" xlink:title="AmortizationOfIntangibleAssets" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_OperatingIncomeLoss" xlink:to="us-gaap_AmortizationOfIntangibleAssets" xlink:title="calculation: us-gaap_OperatingIncomeLoss to us-gaap_AmortizationOfIntangibleAssets" use="optional" order="11.0" weight="-1" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_GainLossOnDispositionOfAssets" xlink:label="us-gaap_GainLossOnDispositionOfAssets" xlink:title="GainLossOnDispositionOfAssets" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_OperatingIncomeLoss" xlink:to="us-gaap_GainLossOnDispositionOfAssets" xlink:title="calculation: us-gaap_OperatingIncomeLoss to us-gaap_GainLossOnDispositionOfAssets" use="optional" order="12.0" weight="1" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_AssetRetirementObligationAccretionExpense" xlink:label="us-gaap_AssetRetirementObligationAccretionExpense" xlink:title="AssetRetirementObligationAccretionExpense" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_OperatingIncomeLoss" xlink:to="us-gaap_AssetRetirementObligationAccretionExpense" xlink:title="calculation: us-gaap_OperatingIncomeLoss to us-gaap_AssetRetirementObligationAccretionExpense" use="optional" order="13.0" weight="-1" />
  </link:calculationLink>
  <link:calculationLink xlink:type="extended" xlink:role="http://www.markwest.com/role/DisclosureIncomeTaxesDetails">
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_IncomeTaxExpenseBenefit" xlink:label="us-gaap_IncomeTaxExpenseBenefit" xlink:title="IncomeTaxExpenseBenefit" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_IncomeTaxReconciliationIncomeTaxExpenseBenefitAtFederalStatutoryIncomeTaxRate" xlink:label="us-gaap_IncomeTaxReconciliationIncomeTaxExpenseBenefitAtFederalStatutoryIncomeTaxRate" xlink:title="IncomeTaxReconciliationIncomeTaxExpenseBenefitAtFederalStatutoryIncomeTaxRate" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_IncomeTaxExpenseBenefit" xlink:to="us-gaap_IncomeTaxReconciliationIncomeTaxExpenseBenefitAtFederalStatutoryIncomeTaxRate" xlink:title="calculation: us-gaap_IncomeTaxExpenseBenefit to us-gaap_IncomeTaxReconciliationIncomeTaxExpenseBenefitAtFederalStatutoryIncomeTaxRate" use="optional" order="1.0" weight="1" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_IncomeTaxReconciliationNondeductibleExpense" xlink:label="us-gaap_IncomeTaxReconciliationNondeductibleExpense" xlink:title="IncomeTaxReconciliationNondeductibleExpense" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_IncomeTaxExpenseBenefit" xlink:to="us-gaap_IncomeTaxReconciliationNondeductibleExpense" xlink:title="calculation: us-gaap_IncomeTaxExpenseBenefit to us-gaap_IncomeTaxReconciliationNondeductibleExpense" use="optional" order="2.0" weight="1" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_IncomeTaxReconciliationStateAndLocalIncomeTaxes" xlink:label="us-gaap_IncomeTaxReconciliationStateAndLocalIncomeTaxes" xlink:title="IncomeTaxReconciliationStateAndLocalIncomeTaxes" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_IncomeTaxExpenseBenefit" xlink:to="us-gaap_IncomeTaxReconciliationStateAndLocalIncomeTaxes" xlink:title="calculation: us-gaap_IncomeTaxExpenseBenefit to us-gaap_IncomeTaxReconciliationStateAndLocalIncomeTaxes" use="optional" order="3.0" weight="1" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_IncomeTaxReconciliationChangeInEnactedTaxRate" xlink:label="us-gaap_IncomeTaxReconciliationChangeInEnactedTaxRate" xlink:title="IncomeTaxReconciliationChangeInEnactedTaxRate" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_IncomeTaxExpenseBenefit" xlink:to="us-gaap_IncomeTaxReconciliationChangeInEnactedTaxRate" xlink:title="calculation: us-gaap_IncomeTaxExpenseBenefit to us-gaap_IncomeTaxReconciliationChangeInEnactedTaxRate" use="optional" order="4.0" weight="1" />
    <link:loc xlink:type="locator" xlink:href="mwe-20140630.xsd#mwe_IncomeTaxReconciliationExpenseBenefitOnIncomeFromClassAUnits" xlink:label="mwe_IncomeTaxReconciliationExpenseBenefitOnIncomeFromClassAUnits" xlink:title="IncomeTaxReconciliationExpenseBenefitOnIncomeFromClassAUnits" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_IncomeTaxExpenseBenefit" xlink:to="mwe_IncomeTaxReconciliationExpenseBenefitOnIncomeFromClassAUnits" xlink:title="calculation: us-gaap_IncomeTaxExpenseBenefit to mwe_IncomeTaxReconciliationExpenseBenefitOnIncomeFromClassAUnits" use="optional" order="5.0" weight="1" />
  </link:calculationLink>
  <link:calculationLink xlink:type="extended" xlink:role="http://www.markwest.com/role/DisclosureInventoriesDetails">
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_InventoryNet" xlink:label="us-gaap_InventoryNet" xlink:title="InventoryNet" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_EnergyRelatedInventoryNaturalGasLiquids" xlink:label="us-gaap_EnergyRelatedInventoryNaturalGasLiquids" xlink:title="EnergyRelatedInventoryNaturalGasLiquids" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_InventoryNet" xlink:to="us-gaap_EnergyRelatedInventoryNaturalGasLiquids" xlink:title="calculation: us-gaap_InventoryNet to us-gaap_EnergyRelatedInventoryNaturalGasLiquids" use="optional" order="1.0" weight="1" />
    <link:loc xlink:type="locator" xlink:href="mwe-20140630.xsd#mwe_NaturalGasOrNaturalGasLiquidsInStorage" xlink:label="mwe_NaturalGasOrNaturalGasLiquidsInStorage" xlink:title="NaturalGasOrNaturalGasLiquidsInStorage" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_InventoryNet" xlink:to="mwe_NaturalGasOrNaturalGasLiquidsInStorage" xlink:title="calculation: us-gaap_InventoryNet to mwe_NaturalGasOrNaturalGasLiquidsInStorage" order="2.0" weight="1" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_OtherInventoriesSpareParts" xlink:label="us-gaap_OtherInventoriesSpareParts" xlink:title="OtherInventoriesSpareParts" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_InventoryNet" xlink:to="us-gaap_OtherInventoriesSpareParts" xlink:title="calculation: us-gaap_InventoryNet to us-gaap_OtherInventoriesSpareParts" use="optional" order="3.0" weight="1" />
  </link:calculationLink>
  <link:calculationLink xlink:type="extended" xlink:role="http://www.markwest.com/role/DisclosureEarningsLossPerCommonUnitDetails">
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_NetIncomeLossAvailableToCommonStockholdersDiluted" xlink:label="us-gaap_NetIncomeLossAvailableToCommonStockholdersDiluted" xlink:title="NetIncomeLossAvailableToCommonStockholdersDiluted" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_NetIncomeLossAvailableToCommonStockholdersBasic" xlink:label="us-gaap_NetIncomeLossAvailableToCommonStockholdersBasic" xlink:title="NetIncomeLossAvailableToCommonStockholdersBasic" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_NetIncomeLossAvailableToCommonStockholdersDiluted" xlink:to="us-gaap_NetIncomeLossAvailableToCommonStockholdersBasic" xlink:title="calculation: us-gaap_NetIncomeLossAvailableToCommonStockholdersDiluted to us-gaap_NetIncomeLossAvailableToCommonStockholdersBasic" use="optional" order="1.0" weight="1" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_NetIncomeLoss" xlink:label="us-gaap_NetIncomeLoss" xlink:title="NetIncomeLoss" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_NetIncomeLossAvailableToCommonStockholdersBasic" xlink:to="us-gaap_NetIncomeLoss" xlink:title="calculation: us-gaap_NetIncomeLossAvailableToCommonStockholdersBasic to us-gaap_NetIncomeLoss" order="1.0" weight="1" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ParticipatingSecuritiesDistributedAndUndistributedEarnings" xlink:label="us-gaap_ParticipatingSecuritiesDistributedAndUndistributedEarnings" xlink:title="ParticipatingSecuritiesDistributedAndUndistributedEarnings" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_NetIncomeLossAvailableToCommonStockholdersBasic" xlink:to="us-gaap_ParticipatingSecuritiesDistributedAndUndistributedEarnings" xlink:title="calculation: us-gaap_NetIncomeLossAvailableToCommonStockholdersBasic to us-gaap_ParticipatingSecuritiesDistributedAndUndistributedEarnings" order="2.0" weight="-1" />
    <link:loc xlink:type="locator" xlink:href="mwe-20140630.xsd#mwe_ParticipatingSecuritiesDistributedAndDividendEquivalentRightsExpense" xlink:label="mwe_ParticipatingSecuritiesDistributedAndDividendEquivalentRightsExpense" xlink:title="ParticipatingSecuritiesDistributedAndDividendEquivalentRightsExpense" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_NetIncomeLossAvailableToCommonStockholdersDiluted" xlink:to="mwe_ParticipatingSecuritiesDistributedAndDividendEquivalentRightsExpense" xlink:title="calculation: us-gaap_NetIncomeLossAvailableToCommonStockholdersDiluted to mwe_ParticipatingSecuritiesDistributedAndDividendEquivalentRightsExpense" use="optional" order="2.0" weight="1" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_WeightedAverageLimitedPartnershipUnitsOutstandingDiluted" xlink:label="us-gaap_WeightedAverageLimitedPartnershipUnitsOutstandingDiluted" xlink:title="WeightedAverageLimitedPartnershipUnitsOutstandingDiluted" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_WeightedAverageLimitedPartnershipUnitsOutstanding" xlink:label="us-gaap_WeightedAverageLimitedPartnershipUnitsOutstanding" xlink:title="WeightedAverageLimitedPartnershipUnitsOutstanding" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_WeightedAverageLimitedPartnershipUnitsOutstandingDiluted" xlink:to="us-gaap_WeightedAverageLimitedPartnershipUnitsOutstanding" xlink:title="calculation: us-gaap_WeightedAverageLimitedPartnershipUnitsOutstandingDiluted to us-gaap_WeightedAverageLimitedPartnershipUnitsOutstanding" order="1.0" weight="1" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_WeightedAverageNumberDilutedSharesOutstandingAdjustment" xlink:label="us-gaap_WeightedAverageNumberDilutedSharesOutstandingAdjustment" xlink:title="WeightedAverageNumberDilutedSharesOutstandingAdjustment" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_WeightedAverageLimitedPartnershipUnitsOutstandingDiluted" xlink:to="us-gaap_WeightedAverageNumberDilutedSharesOutstandingAdjustment" xlink:title="calculation: us-gaap_WeightedAverageLimitedPartnershipUnitsOutstandingDiluted to us-gaap_WeightedAverageNumberDilutedSharesOutstandingAdjustment" use="optional" order="2.0" weight="1" />
  </link:calculationLink>
  <link:calculationLink xlink:type="extended" xlink:role="http://www.markwest.com/role/DisclosureDerivativeFinancialInstrumentsDetails3">
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_DerivativeFairValueOfDerivativeAssetAmountNotOffsetAgainstCollateral" xlink:label="us-gaap_DerivativeFairValueOfDerivativeAssetAmountNotOffsetAgainstCollateral" xlink:title="DerivativeFairValueOfDerivativeAssetAmountNotOffsetAgainstCollateral" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_DerivativeFairValueOfDerivativeAsset" xlink:label="us-gaap_DerivativeFairValueOfDerivativeAsset" xlink:title="DerivativeFairValueOfDerivativeAsset" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_DerivativeFairValueOfDerivativeAssetAmountNotOffsetAgainstCollateral" xlink:to="us-gaap_DerivativeFairValueOfDerivativeAsset" xlink:title="calculation: us-gaap_DerivativeFairValueOfDerivativeAssetAmountNotOffsetAgainstCollateral to us-gaap_DerivativeFairValueOfDerivativeAsset" use="optional" order="1.0" weight="1" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_DerivativeAssetFairValueGrossLiability" xlink:label="us-gaap_DerivativeAssetFairValueGrossLiability" xlink:title="DerivativeAssetFairValueGrossLiability" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_DerivativeFairValueOfDerivativeAssetAmountNotOffsetAgainstCollateral" xlink:to="us-gaap_DerivativeAssetFairValueGrossLiability" xlink:title="calculation: us-gaap_DerivativeFairValueOfDerivativeAssetAmountNotOffsetAgainstCollateral to us-gaap_DerivativeAssetFairValueGrossLiability" use="optional" order="2.0" weight="-1" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_DerivativeFairValueOfDerivativeLiabilityAmountNotOffsetAgainstCollateral" xlink:label="us-gaap_DerivativeFairValueOfDerivativeLiabilityAmountNotOffsetAgainstCollateral" xlink:title="DerivativeFairValueOfDerivativeLiabilityAmountNotOffsetAgainstCollateral" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_DerivativeFairValueOfDerivativeLiability" xlink:label="us-gaap_DerivativeFairValueOfDerivativeLiability" xlink:title="DerivativeFairValueOfDerivativeLiability" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_DerivativeFairValueOfDerivativeLiabilityAmountNotOffsetAgainstCollateral" xlink:to="us-gaap_DerivativeFairValueOfDerivativeLiability" xlink:title="calculation: us-gaap_DerivativeFairValueOfDerivativeLiabilityAmountNotOffsetAgainstCollateral to us-gaap_DerivativeFairValueOfDerivativeLiability" use="optional" order="1.0" weight="1" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_DerivativeLiabilityFairValueGrossAsset" xlink:label="us-gaap_DerivativeLiabilityFairValueGrossAsset" xlink:title="DerivativeLiabilityFairValueGrossAsset" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_DerivativeFairValueOfDerivativeLiabilityAmountNotOffsetAgainstCollateral" xlink:to="us-gaap_DerivativeLiabilityFairValueGrossAsset" xlink:title="calculation: us-gaap_DerivativeFairValueOfDerivativeLiabilityAmountNotOffsetAgainstCollateral to us-gaap_DerivativeLiabilityFairValueGrossAsset" use="optional" order="2.0" weight="-1" />
  </link:calculationLink>
  <link:calculationLink xlink:type="extended" xlink:role="http://www.markwest.com/role/BalanceSheet">
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_Assets" xlink:label="us-gaap_Assets" xlink:title="Assets" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_AssetsCurrent" xlink:label="us-gaap_AssetsCurrent" xlink:title="AssetsCurrent" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_Assets" xlink:to="us-gaap_AssetsCurrent" xlink:title="calculation: us-gaap_Assets to us-gaap_AssetsCurrent" order="1.0" weight="1" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_CashAndCashEquivalentsAtCarryingValue" xlink:label="us-gaap_CashAndCashEquivalentsAtCarryingValue" xlink:title="CashAndCashEquivalentsAtCarryingValue" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_AssetsCurrent" xlink:to="us-gaap_CashAndCashEquivalentsAtCarryingValue" xlink:title="calculation: us-gaap_AssetsCurrent to us-gaap_CashAndCashEquivalentsAtCarryingValue" use="optional" order="1.0" weight="1" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_RestrictedCashAndCashEquivalentsAtCarryingValue" xlink:label="us-gaap_RestrictedCashAndCashEquivalentsAtCarryingValue" xlink:title="RestrictedCashAndCashEquivalentsAtCarryingValue" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_AssetsCurrent" xlink:to="us-gaap_RestrictedCashAndCashEquivalentsAtCarryingValue" xlink:title="calculation: us-gaap_AssetsCurrent to us-gaap_RestrictedCashAndCashEquivalentsAtCarryingValue" use="optional" order="2.0" weight="1" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ReceivablesNetCurrent" xlink:label="us-gaap_ReceivablesNetCurrent" xlink:title="ReceivablesNetCurrent" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_AssetsCurrent" xlink:to="us-gaap_ReceivablesNetCurrent" xlink:title="calculation: us-gaap_AssetsCurrent to us-gaap_ReceivablesNetCurrent" use="optional" order="3.0" weight="1" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_AccountsReceivableRelatedPartiesCurrent" xlink:label="us-gaap_AccountsReceivableRelatedPartiesCurrent" xlink:title="AccountsReceivableRelatedPartiesCurrent" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_AssetsCurrent" xlink:to="us-gaap_AccountsReceivableRelatedPartiesCurrent" xlink:title="calculation: us-gaap_AssetsCurrent to us-gaap_AccountsReceivableRelatedPartiesCurrent" order="4.0" weight="1" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_InventoryNet" xlink:label="us-gaap_InventoryNet" xlink:title="InventoryNet" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_AssetsCurrent" xlink:to="us-gaap_InventoryNet" xlink:title="calculation: us-gaap_AssetsCurrent to us-gaap_InventoryNet" use="optional" order="5.0" weight="1" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_DerivativeAssetsCurrent" xlink:label="us-gaap_DerivativeAssetsCurrent" xlink:title="DerivativeAssetsCurrent" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_AssetsCurrent" xlink:to="us-gaap_DerivativeAssetsCurrent" xlink:title="calculation: us-gaap_AssetsCurrent to us-gaap_DerivativeAssetsCurrent" use="optional" order="6.0" weight="1" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_DeferredTaxAssetsLiabilitiesNetCurrent" xlink:label="us-gaap_DeferredTaxAssetsLiabilitiesNetCurrent" xlink:title="DeferredTaxAssetsLiabilitiesNetCurrent" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_AssetsCurrent" xlink:to="us-gaap_DeferredTaxAssetsLiabilitiesNetCurrent" xlink:title="calculation: us-gaap_AssetsCurrent to us-gaap_DeferredTaxAssetsLiabilitiesNetCurrent" use="optional" order="7.0" weight="1" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_OtherAssetsCurrent" xlink:label="us-gaap_OtherAssetsCurrent" xlink:title="OtherAssetsCurrent" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_AssetsCurrent" xlink:to="us-gaap_OtherAssetsCurrent" xlink:title="calculation: us-gaap_AssetsCurrent to us-gaap_OtherAssetsCurrent" use="optional" order="8.0" weight="1" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_PropertyPlantAndEquipmentNet" xlink:label="us-gaap_PropertyPlantAndEquipmentNet" xlink:title="PropertyPlantAndEquipmentNet" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_Assets" xlink:to="us-gaap_PropertyPlantAndEquipmentNet" xlink:title="calculation: us-gaap_Assets to us-gaap_PropertyPlantAndEquipmentNet" order="2.0" weight="1" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_PropertyPlantAndEquipmentGross" xlink:label="us-gaap_PropertyPlantAndEquipmentGross" xlink:title="PropertyPlantAndEquipmentGross" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_PropertyPlantAndEquipmentNet" xlink:to="us-gaap_PropertyPlantAndEquipmentGross" xlink:title="calculation: us-gaap_PropertyPlantAndEquipmentNet to us-gaap_PropertyPlantAndEquipmentGross" order="1.0" weight="1" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment" xlink:label="us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment" xlink:title="AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_PropertyPlantAndEquipmentNet" xlink:to="us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment" xlink:title="calculation: us-gaap_PropertyPlantAndEquipmentNet to us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment" order="2.0" weight="-1" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_RestrictedCashAndCashEquivalentsNoncurrent" xlink:label="us-gaap_RestrictedCashAndCashEquivalentsNoncurrent" xlink:title="RestrictedCashAndCashEquivalentsNoncurrent" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_Assets" xlink:to="us-gaap_RestrictedCashAndCashEquivalentsNoncurrent" xlink:title="calculation: us-gaap_Assets to us-gaap_RestrictedCashAndCashEquivalentsNoncurrent" use="optional" order="3.0" weight="1" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_EquityMethodInvestments" xlink:label="us-gaap_EquityMethodInvestments" xlink:title="EquityMethodInvestments" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_Assets" xlink:to="us-gaap_EquityMethodInvestments" xlink:title="calculation: us-gaap_Assets to us-gaap_EquityMethodInvestments" use="optional" order="4.0" weight="1" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsNet" xlink:label="us-gaap_FiniteLivedIntangibleAssetsNet" xlink:title="FiniteLivedIntangibleAssetsNet" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_Assets" xlink:to="us-gaap_FiniteLivedIntangibleAssetsNet" xlink:title="calculation: us-gaap_Assets to us-gaap_FiniteLivedIntangibleAssetsNet" use="optional" order="5.0" weight="1" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_Goodwill" xlink:label="us-gaap_Goodwill" xlink:title="Goodwill" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_Assets" xlink:to="us-gaap_Goodwill" xlink:title="calculation: us-gaap_Assets to us-gaap_Goodwill" use="optional" order="6.0" weight="1" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_DeferredFinanceCostsNoncurrentNet" xlink:label="us-gaap_DeferredFinanceCostsNoncurrentNet" xlink:title="DeferredFinanceCostsNoncurrentNet" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_Assets" xlink:to="us-gaap_DeferredFinanceCostsNoncurrentNet" xlink:title="calculation: us-gaap_Assets to us-gaap_DeferredFinanceCostsNoncurrentNet" use="optional" order="7.0" weight="1" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_OtherDeferredCostsNet" xlink:label="us-gaap_OtherDeferredCostsNet" xlink:title="OtherDeferredCostsNet" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_Assets" xlink:to="us-gaap_OtherDeferredCostsNet" xlink:title="calculation: us-gaap_Assets to us-gaap_OtherDeferredCostsNet" use="optional" order="8.0" weight="1" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_DerivativeAssetsNoncurrent" xlink:label="us-gaap_DerivativeAssetsNoncurrent" xlink:title="DerivativeAssetsNoncurrent" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_Assets" xlink:to="us-gaap_DerivativeAssetsNoncurrent" xlink:title="calculation: us-gaap_Assets to us-gaap_DerivativeAssetsNoncurrent" use="optional" order="9.0" weight="1" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_OtherAssetsNoncurrent" xlink:label="us-gaap_OtherAssetsNoncurrent" xlink:title="OtherAssetsNoncurrent" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_Assets" xlink:to="us-gaap_OtherAssetsNoncurrent" xlink:title="calculation: us-gaap_Assets to us-gaap_OtherAssetsNoncurrent" use="optional" order="10.0" weight="1" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_LiabilitiesCurrent" xlink:label="us-gaap_LiabilitiesCurrent" xlink:title="LiabilitiesCurrent" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_AccountsPayableCurrent" xlink:label="us-gaap_AccountsPayableCurrent" xlink:title="AccountsPayableCurrent" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_LiabilitiesCurrent" xlink:to="us-gaap_AccountsPayableCurrent" xlink:title="calculation: us-gaap_LiabilitiesCurrent to us-gaap_AccountsPayableCurrent" use="optional" order="1.0" weight="1" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_AccruedLiabilitiesCurrent" xlink:label="us-gaap_AccruedLiabilitiesCurrent" xlink:title="AccruedLiabilitiesCurrent" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_LiabilitiesCurrent" xlink:to="us-gaap_AccruedLiabilitiesCurrent" xlink:title="calculation: us-gaap_LiabilitiesCurrent to us-gaap_AccruedLiabilitiesCurrent" use="optional" order="2.0" weight="1" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_DerivativeLiabilitiesCurrent" xlink:label="us-gaap_DerivativeLiabilitiesCurrent" xlink:title="DerivativeLiabilitiesCurrent" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_LiabilitiesCurrent" xlink:to="us-gaap_DerivativeLiabilitiesCurrent" xlink:title="calculation: us-gaap_LiabilitiesCurrent to us-gaap_DerivativeLiabilitiesCurrent" use="optional" order="3.0" weight="1" />
  </link:calculationLink>
  <link:calculationLink xlink:type="extended" xlink:role="http://www.markwest.com/role/DisclosureSupplementalCondensedConsolidatingFinancialInformationDetails">
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_Assets" xlink:label="us-gaap_Assets" xlink:title="Assets" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_AssetsCurrent" xlink:label="us-gaap_AssetsCurrent" xlink:title="AssetsCurrent" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_Assets" xlink:to="us-gaap_AssetsCurrent" xlink:title="calculation: us-gaap_Assets to us-gaap_AssetsCurrent" use="optional" order="1.0" weight="1" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_CashAndCashEquivalentsAtCarryingValue" xlink:label="us-gaap_CashAndCashEquivalentsAtCarryingValue" xlink:title="CashAndCashEquivalentsAtCarryingValue" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_AssetsCurrent" xlink:to="us-gaap_CashAndCashEquivalentsAtCarryingValue" xlink:title="calculation: us-gaap_AssetsCurrent to us-gaap_CashAndCashEquivalentsAtCarryingValue" use="optional" order="1.0" weight="1" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_RestrictedCashAndCashEquivalentsAtCarryingValue" xlink:label="us-gaap_RestrictedCashAndCashEquivalentsAtCarryingValue" xlink:title="RestrictedCashAndCashEquivalentsAtCarryingValue" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_AssetsCurrent" xlink:to="us-gaap_RestrictedCashAndCashEquivalentsAtCarryingValue" xlink:title="calculation: us-gaap_AssetsCurrent to us-gaap_RestrictedCashAndCashEquivalentsAtCarryingValue" order="2.0" weight="1" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_AccountsReceivableRelatedPartiesCurrent" xlink:label="us-gaap_AccountsReceivableRelatedPartiesCurrent" xlink:title="AccountsReceivableRelatedPartiesCurrent" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_AssetsCurrent" xlink:to="us-gaap_AccountsReceivableRelatedPartiesCurrent" xlink:title="calculation: us-gaap_AssetsCurrent to us-gaap_AccountsReceivableRelatedPartiesCurrent" use="optional" order="6.0" weight="1" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_DerivativeAssetsCurrent" xlink:label="us-gaap_DerivativeAssetsCurrent" xlink:title="DerivativeAssetsCurrent" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_AssetsCurrent" xlink:to="us-gaap_DerivativeAssetsCurrent" xlink:title="calculation: us-gaap_AssetsCurrent to us-gaap_DerivativeAssetsCurrent" use="optional" order="5.0" weight="1" />
    <link:loc xlink:type="locator" xlink:href="mwe-20140630.xsd#mwe_ReceivablesAndOtherAssetsCurrent" xlink:label="mwe_ReceivablesAndOtherAssetsCurrent" xlink:title="ReceivablesAndOtherAssetsCurrent" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_AssetsCurrent" xlink:to="mwe_ReceivablesAndOtherAssetsCurrent" xlink:title="calculation: us-gaap_AssetsCurrent to mwe_ReceivablesAndOtherAssetsCurrent" use="optional" order="3.0" weight="1" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_DueFromAffiliateCurrent" xlink:label="us-gaap_DueFromAffiliateCurrent" xlink:title="DueFromAffiliateCurrent" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_AssetsCurrent" xlink:to="us-gaap_DueFromAffiliateCurrent" xlink:title="calculation: us-gaap_AssetsCurrent to us-gaap_DueFromAffiliateCurrent" use="optional" order="4.0" weight="1" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_PropertyPlantAndEquipmentNet" xlink:label="us-gaap_PropertyPlantAndEquipmentNet" xlink:title="PropertyPlantAndEquipmentNet" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_Assets" xlink:to="us-gaap_PropertyPlantAndEquipmentNet" xlink:title="calculation: us-gaap_Assets to us-gaap_PropertyPlantAndEquipmentNet" use="optional" order="2.0" weight="1" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_RestrictedCashAndCashEquivalentsNoncurrent" xlink:label="us-gaap_RestrictedCashAndCashEquivalentsNoncurrent" xlink:title="RestrictedCashAndCashEquivalentsNoncurrent" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_Assets" xlink:to="us-gaap_RestrictedCashAndCashEquivalentsNoncurrent" xlink:title="calculation: us-gaap_Assets to us-gaap_RestrictedCashAndCashEquivalentsNoncurrent" order="3.0" weight="1" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_EquityMethodInvestments" xlink:label="us-gaap_EquityMethodInvestments" xlink:title="EquityMethodInvestments" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_Assets" xlink:to="us-gaap_EquityMethodInvestments" xlink:title="calculation: us-gaap_Assets to us-gaap_EquityMethodInvestments" use="optional" order="4.0" weight="1" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsNet" xlink:label="us-gaap_FiniteLivedIntangibleAssetsNet" xlink:title="FiniteLivedIntangibleAssetsNet" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_Assets" xlink:to="us-gaap_FiniteLivedIntangibleAssetsNet" xlink:title="calculation: us-gaap_Assets to us-gaap_FiniteLivedIntangibleAssetsNet" use="optional" order="6.0" weight="1" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_DerivativeAssetsNoncurrent" xlink:label="us-gaap_DerivativeAssetsNoncurrent" xlink:title="DerivativeAssetsNoncurrent" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_Assets" xlink:to="us-gaap_DerivativeAssetsNoncurrent" xlink:title="calculation: us-gaap_Assets to us-gaap_DerivativeAssetsNoncurrent" use="optional" order="7.0" weight="1" />
    <link:loc xlink:type="locator" xlink:href="mwe-20140630.xsd#mwe_InvestmentInAffiliates" xlink:label="mwe_InvestmentInAffiliates" xlink:title="InvestmentInAffiliates" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_Assets" xlink:to="mwe_InvestmentInAffiliates" xlink:title="calculation: us-gaap_Assets to mwe_InvestmentInAffiliates" use="optional" order="5.0" weight="1" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_DueFromAffiliateNoncurrent" xlink:label="us-gaap_DueFromAffiliateNoncurrent" xlink:title="DueFromAffiliateNoncurrent" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_Assets" xlink:to="us-gaap_DueFromAffiliateNoncurrent" xlink:title="calculation: us-gaap_Assets to us-gaap_DueFromAffiliateNoncurrent" use="optional" order="8.0" weight="1" />
    <link:loc xlink:type="locator" xlink:href="mwe-20140630.xsd#mwe_OtherAssetNoncurrentCondensedSupplemental" xlink:label="mwe_OtherAssetNoncurrentCondensedSupplemental" xlink:title="OtherAssetNoncurrentCondensedSupplemental" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_Assets" xlink:to="mwe_OtherAssetNoncurrentCondensedSupplemental" xlink:title="calculation: us-gaap_Assets to mwe_OtherAssetNoncurrentCondensedSupplemental" use="optional" order="9.0" weight="1" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_LiabilitiesAndStockholdersEquity" xlink:label="us-gaap_LiabilitiesAndStockholdersEquity" xlink:title="LiabilitiesAndStockholdersEquity" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_LiabilitiesCurrent" xlink:label="us-gaap_LiabilitiesCurrent" xlink:title="LiabilitiesCurrent" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_LiabilitiesAndStockholdersEquity" xlink:to="us-gaap_LiabilitiesCurrent" xlink:title="calculation: us-gaap_LiabilitiesAndStockholdersEquity to us-gaap_LiabilitiesCurrent" use="optional" order="1.0" weight="1" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_DerivativeLiabilitiesCurrent" xlink:label="us-gaap_DerivativeLiabilitiesCurrent" xlink:title="DerivativeLiabilitiesCurrent" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_LiabilitiesCurrent" xlink:to="us-gaap_DerivativeLiabilitiesCurrent" xlink:title="calculation: us-gaap_LiabilitiesCurrent to us-gaap_DerivativeLiabilitiesCurrent" use="optional" order="2.0" weight="1" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_DueToAffiliateCurrent" xlink:label="us-gaap_DueToAffiliateCurrent" xlink:title="DueToAffiliateCurrent" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_LiabilitiesCurrent" xlink:to="us-gaap_DueToAffiliateCurrent" xlink:title="calculation: us-gaap_LiabilitiesCurrent to us-gaap_DueToAffiliateCurrent" use="optional" order="1.0" weight="1" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_OtherLiabilitiesCurrent" xlink:label="us-gaap_OtherLiabilitiesCurrent" xlink:title="OtherLiabilitiesCurrent" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_LiabilitiesCurrent" xlink:to="us-gaap_OtherLiabilitiesCurrent" xlink:title="calculation: us-gaap_LiabilitiesCurrent to us-gaap_OtherLiabilitiesCurrent" use="optional" order="3.0" weight="1" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_DeferredTaxLiabilitiesNoncurrent" xlink:label="us-gaap_DeferredTaxLiabilitiesNoncurrent" xlink:title="DeferredTaxLiabilitiesNoncurrent" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_LiabilitiesAndStockholdersEquity" xlink:to="us-gaap_DeferredTaxLiabilitiesNoncurrent" xlink:title="calculation: us-gaap_LiabilitiesAndStockholdersEquity to us-gaap_DeferredTaxLiabilitiesNoncurrent" use="optional" order="2.0" weight="1" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_DueToAffiliateNoncurrent" xlink:label="us-gaap_DueToAffiliateNoncurrent" xlink:title="DueToAffiliateNoncurrent" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_LiabilitiesAndStockholdersEquity" xlink:to="us-gaap_DueToAffiliateNoncurrent" xlink:title="calculation: us-gaap_LiabilitiesAndStockholdersEquity to us-gaap_DueToAffiliateNoncurrent" use="optional" order="3.0" weight="1" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_DerivativeLiabilitiesNoncurrent" xlink:label="us-gaap_DerivativeLiabilitiesNoncurrent" xlink:title="DerivativeLiabilitiesNoncurrent" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_LiabilitiesAndStockholdersEquity" xlink:to="us-gaap_DerivativeLiabilitiesNoncurrent" xlink:title="calculation: us-gaap_LiabilitiesAndStockholdersEquity to us-gaap_DerivativeLiabilitiesNoncurrent" use="optional" order="4.0" weight="1" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_LongTermDebtNoncurrent" xlink:label="us-gaap_LongTermDebtNoncurrent" xlink:title="LongTermDebtNoncurrent" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_LiabilitiesAndStockholdersEquity" xlink:to="us-gaap_LongTermDebtNoncurrent" xlink:title="calculation: us-gaap_LiabilitiesAndStockholdersEquity to us-gaap_LongTermDebtNoncurrent" use="optional" order="5.0" weight="1" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_OtherLiabilitiesNoncurrent" xlink:label="us-gaap_OtherLiabilitiesNoncurrent" xlink:title="OtherLiabilitiesNoncurrent" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_LiabilitiesAndStockholdersEquity" xlink:to="us-gaap_OtherLiabilitiesNoncurrent" xlink:title="calculation: us-gaap_LiabilitiesAndStockholdersEquity to us-gaap_OtherLiabilitiesNoncurrent" use="optional" order="6.0" weight="1" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_RedeemableNoncontrollingInterestEquityCarryingAmount" xlink:label="us-gaap_RedeemableNoncontrollingInterestEquityCarryingAmount" xlink:title="RedeemableNoncontrollingInterestEquityCarryingAmount" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_LiabilitiesAndStockholdersEquity" xlink:to="us-gaap_RedeemableNoncontrollingInterestEquityCarryingAmount" xlink:title="calculation: us-gaap_LiabilitiesAndStockholdersEquity to us-gaap_RedeemableNoncontrollingInterestEquityCarryingAmount" use="optional" order="7.0" weight="1" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest" xlink:label="us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest" xlink:title="StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_LiabilitiesAndStockholdersEquity" xlink:to="us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest" xlink:title="calculation: us-gaap_LiabilitiesAndStockholdersEquity to us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest" use="optional" order="8.0" weight="1" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_LimitedPartnersCapitalAccount" xlink:label="us-gaap_LimitedPartnersCapitalAccount" xlink:title="LimitedPartnersCapitalAccount" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest" xlink:to="us-gaap_LimitedPartnersCapitalAccount" xlink:title="calculation: us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest to us-gaap_LimitedPartnersCapitalAccount" use="optional" order="1.0" weight="1" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_MinorityInterest" xlink:label="us-gaap_MinorityInterest" xlink:title="MinorityInterest" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest" xlink:to="us-gaap_MinorityInterest" xlink:title="calculation: us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest to us-gaap_MinorityInterest" use="optional" order="2.0" weight="1" />
  </link:calculationLink>
  <link:calculationLink xlink:type="extended" xlink:role="http://www.markwest.com/role/DisclosureDerivativeFinancialInstrumentsDetails">
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_EmbeddedDerivativeFairValueOfEmbeddedDerivativeLiability" xlink:label="us-gaap_EmbeddedDerivativeFairValueOfEmbeddedDerivativeLiability" xlink:title="EmbeddedDerivativeFairValueOfEmbeddedDerivativeLiability" />
    <link:loc xlink:type="locator" xlink:href="mwe-20140630.xsd#mwe_EmbeddedDerivativeFairValueOfEmbeddedDerivativeLiabilityIncludingInceptionValueAllocableToHostContract" xlink:label="mwe_EmbeddedDerivativeFairValueOfEmbeddedDerivativeLiabilityIncludingInceptionValueAllocableToHostContract" xlink:title="EmbeddedDerivativeFairValueOfEmbeddedDerivativeLiabilityIncludingInceptionValueAllocableToHostContract" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_EmbeddedDerivativeFairValueOfEmbeddedDerivativeLiability" xlink:to="mwe_EmbeddedDerivativeFairValueOfEmbeddedDerivativeLiabilityIncludingInceptionValueAllocableToHostContract" xlink:title="calculation: us-gaap_EmbeddedDerivativeFairValueOfEmbeddedDerivativeLiability to mwe_EmbeddedDerivativeFairValueOfEmbeddedDerivativeLiabilityIncludingInceptionValueAllocableToHostContract" use="optional" order="1.0" weight="1" />
    <link:loc xlink:type="locator" xlink:href="mwe-20140630.xsd#mwe_EmbeddedDerivativeFairValueOfEmbeddedDerivativeLiabilityContractRelatedAtInceptionOfExtendedPeriod" xlink:label="mwe_EmbeddedDerivativeFairValueOfEmbeddedDerivativeLiabilityContractRelatedAtInceptionOfExtendedPeriod" xlink:title="EmbeddedDerivativeFairValueOfEmbeddedDerivativeLiabilityContractRelatedAtInceptionOfExtendedPeriod" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_EmbeddedDerivativeFairValueOfEmbeddedDerivativeLiability" xlink:to="mwe_EmbeddedDerivativeFairValueOfEmbeddedDerivativeLiabilityContractRelatedAtInceptionOfExtendedPeriod" xlink:title="calculation: us-gaap_EmbeddedDerivativeFairValueOfEmbeddedDerivativeLiability to mwe_EmbeddedDerivativeFairValueOfEmbeddedDerivativeLiabilityContractRelatedAtInceptionOfExtendedPeriod" use="optional" order="2.0" weight="1" />
  </link:calculationLink>
  <link:calculationLink xlink:type="extended" xlink:role="http://www.markwest.com/role/DisclosureSegmentInformationDetails">
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_OperatingIncomeLoss" xlink:label="us-gaap_OperatingIncomeLoss" xlink:title="OperatingIncomeLoss" />
    <link:loc xlink:type="locator" xlink:href="mwe-20140630.xsd#mwe_MinorityInterestInOperatingIncomeLossLimitedPartnerships" xlink:label="mwe_MinorityInterestInOperatingIncomeLossLimitedPartnerships" xlink:title="MinorityInterestInOperatingIncomeLossLimitedPartnerships" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_OperatingIncomeLoss" xlink:to="mwe_MinorityInterestInOperatingIncomeLossLimitedPartnerships" xlink:title="calculation: us-gaap_OperatingIncomeLoss to mwe_MinorityInterestInOperatingIncomeLossLimitedPartnerships" use="optional" order="3.0" weight="-1" />
    <link:loc xlink:type="locator" xlink:href="mwe-20140630.xsd#mwe_NetOperatingMargin" xlink:label="mwe_NetOperatingMargin" xlink:title="NetOperatingMargin" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_OperatingIncomeLoss" xlink:to="mwe_NetOperatingMargin" xlink:title="calculation: us-gaap_OperatingIncomeLoss to mwe_NetOperatingMargin" use="optional" order="1.0" weight="1" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_GasGatheringTransportationMarketingAndProcessingRevenue" xlink:label="us-gaap_GasGatheringTransportationMarketingAndProcessingRevenue" xlink:title="GasGatheringTransportationMarketingAndProcessingRevenue" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="mwe_NetOperatingMargin" xlink:to="us-gaap_GasGatheringTransportationMarketingAndProcessingRevenue" xlink:title="calculation: mwe_NetOperatingMargin to us-gaap_GasGatheringTransportationMarketingAndProcessingRevenue" use="optional" order="1.0" weight="1" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_NaturalGasMidstreamCosts" xlink:label="us-gaap_NaturalGasMidstreamCosts" xlink:title="NaturalGasMidstreamCosts" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="mwe_NetOperatingMargin" xlink:to="us-gaap_NaturalGasMidstreamCosts" xlink:title="calculation: mwe_NetOperatingMargin to us-gaap_NaturalGasMidstreamCosts" use="optional" order="2.0" weight="-1" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_FacilityCosts" xlink:label="us-gaap_FacilityCosts" xlink:title="FacilityCosts" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_OperatingIncomeLoss" xlink:to="us-gaap_FacilityCosts" xlink:title="calculation: us-gaap_OperatingIncomeLoss to us-gaap_FacilityCosts" use="optional" order="2.0" weight="-1" />
  </link:calculationLink>
  <link:calculationLink xlink:type="extended" xlink:role="http://www.markwest.com/role/DisclosureSupplementalCondensedConsolidatingFinancialInformationDetails2">
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest" xlink:label="us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest" xlink:title="IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_OperatingIncomeLoss" xlink:label="us-gaap_OperatingIncomeLoss" xlink:title="OperatingIncomeLoss" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest" xlink:to="us-gaap_OperatingIncomeLoss" xlink:title="calculation: us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest to us-gaap_OperatingIncomeLoss" use="optional" order="1.0" weight="1" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_CostsAndExpenses" xlink:label="us-gaap_CostsAndExpenses" xlink:title="CostsAndExpenses" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_SellingGeneralAndAdministrativeExpense" xlink:label="us-gaap_SellingGeneralAndAdministrativeExpense" xlink:title="SellingGeneralAndAdministrativeExpense" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_CostsAndExpenses" xlink:to="us-gaap_SellingGeneralAndAdministrativeExpense" xlink:title="calculation: us-gaap_CostsAndExpenses to us-gaap_SellingGeneralAndAdministrativeExpense" use="optional" order="3.0" weight="1" />
    <link:loc xlink:type="locator" xlink:href="mwe-20140630.xsd#mwe_NaturalGasMidstreamCostsIncludingGainLossOnPriceRiskDerivativeInstrumentsNotDesignatedAsHedgingInstrumentsRelatedToProductCost" xlink:label="mwe_NaturalGasMidstreamCostsIncludingGainLossOnPriceRiskDerivativeInstrumentsNotDesignatedAsHedgingInstrumentsRelatedToProductCost" xlink:title="NaturalGasMidstreamCostsIncludingGainLossOnPriceRiskDerivativeInstrumentsNotDesignatedAsHedgingInstrumentsRelatedToProductCost" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_CostsAndExpenses" xlink:to="mwe_NaturalGasMidstreamCostsIncludingGainLossOnPriceRiskDerivativeInstrumentsNotDesignatedAsHedgingInstrumentsRelatedToProductCost" xlink:title="calculation: us-gaap_CostsAndExpenses to mwe_NaturalGasMidstreamCostsIncludingGainLossOnPriceRiskDerivativeInstrumentsNotDesignatedAsHedgingInstrumentsRelatedToProductCost" use="optional" order="1.0" weight="1" />
    <link:loc xlink:type="locator" xlink:href="mwe-20140630.xsd#mwe_FacilityCostsIncludingGainLossOnPriceRiskDerivativeInstrumentsNotDesignatedAsHedgingInstrumentsRelatedToFacilityExpense" xlink:label="mwe_FacilityCostsIncludingGainLossOnPriceRiskDerivativeInstrumentsNotDesignatedAsHedgingInstrumentsRelatedToFacilityExpense" xlink:title="FacilityCostsIncludingGainLossOnPriceRiskDerivativeInstrumentsNotDesignatedAsHedgingInstrumentsRelatedToFacilityExpense" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_CostsAndExpenses" xlink:to="mwe_FacilityCostsIncludingGainLossOnPriceRiskDerivativeInstrumentsNotDesignatedAsHedgingInstrumentsRelatedToFacilityExpense" xlink:title="calculation: us-gaap_CostsAndExpenses to mwe_FacilityCostsIncludingGainLossOnPriceRiskDerivativeInstrumentsNotDesignatedAsHedgingInstrumentsRelatedToFacilityExpense" use="optional" order="2.0" weight="1" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_DepreciationAndAmortization" xlink:label="us-gaap_DepreciationAndAmortization" xlink:title="DepreciationAndAmortization" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_CostsAndExpenses" xlink:to="us-gaap_DepreciationAndAmortization" xlink:title="calculation: us-gaap_CostsAndExpenses to us-gaap_DepreciationAndAmortization" use="optional" order="4.0" weight="1" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_OtherCostAndExpenseOperating" xlink:label="us-gaap_OtherCostAndExpenseOperating" xlink:title="OtherCostAndExpenseOperating" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_CostsAndExpenses" xlink:to="us-gaap_OtherCostAndExpenseOperating" xlink:title="calculation: us-gaap_CostsAndExpenses to us-gaap_OtherCostAndExpenseOperating" use="optional" order="5.0" weight="1" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_GainsLossesOnExtinguishmentOfDebt" xlink:label="us-gaap_GainsLossesOnExtinguishmentOfDebt" xlink:title="GainsLossesOnExtinguishmentOfDebt" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest" xlink:to="us-gaap_GainsLossesOnExtinguishmentOfDebt" xlink:title="calculation: us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest to us-gaap_GainsLossesOnExtinguishmentOfDebt" use="optional" order="3.0" weight="1" />
    <link:loc xlink:type="locator" xlink:href="mwe-20140630.xsd#mwe_IncomeLossFromAffiliatesSubsidiariesAndHoldingCompany" xlink:label="mwe_IncomeLossFromAffiliatesSubsidiariesAndHoldingCompany" xlink:title="IncomeLossFromAffiliatesSubsidiariesAndHoldingCompany" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest" xlink:to="mwe_IncomeLossFromAffiliatesSubsidiariesAndHoldingCompany" xlink:title="calculation: us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest to mwe_IncomeLossFromAffiliatesSubsidiariesAndHoldingCompany" use="optional" order="2.0" weight="1" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_NonoperatingIncomeExpense" xlink:label="us-gaap_NonoperatingIncomeExpense" xlink:title="NonoperatingIncomeExpense" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest" xlink:to="us-gaap_NonoperatingIncomeExpense" xlink:title="calculation: us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest to us-gaap_NonoperatingIncomeExpense" use="optional" order="4.0" weight="1" />
  </link:calculationLink>
  <link:calculationLink xlink:type="extended" xlink:role="http://www.markwest.com/role/DisclosureSupplementalCondensedConsolidatingFinancialInformationDetails3">
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_NetCashProvidedByUsedInContinuingOperations" xlink:label="us-gaap_NetCashProvidedByUsedInContinuingOperations" xlink:title="NetCashProvidedByUsedInContinuingOperations" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_NetCashProvidedByUsedInOperatingActivitiesContinuingOperations" xlink:label="us-gaap_NetCashProvidedByUsedInOperatingActivitiesContinuingOperations" xlink:title="NetCashProvidedByUsedInOperatingActivitiesContinuingOperations" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_NetCashProvidedByUsedInContinuingOperations" xlink:to="us-gaap_NetCashProvidedByUsedInOperatingActivitiesContinuingOperations" xlink:title="calculation: us-gaap_NetCashProvidedByUsedInContinuingOperations to us-gaap_NetCashProvidedByUsedInOperatingActivitiesContinuingOperations" use="optional" order="1.0" weight="1" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_NetCashProvidedByUsedInFinancingActivitiesContinuingOperations" xlink:label="us-gaap_NetCashProvidedByUsedInFinancingActivitiesContinuingOperations" xlink:title="NetCashProvidedByUsedInFinancingActivitiesContinuingOperations" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_NetCashProvidedByUsedInContinuingOperations" xlink:to="us-gaap_NetCashProvidedByUsedInFinancingActivitiesContinuingOperations" xlink:title="calculation: us-gaap_NetCashProvidedByUsedInContinuingOperations to us-gaap_NetCashProvidedByUsedInFinancingActivitiesContinuingOperations" order="2.0" weight="1" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ProceedsFromIssuanceOfCommonLimitedPartnersUnits" xlink:label="us-gaap_ProceedsFromIssuanceOfCommonLimitedPartnersUnits" xlink:title="ProceedsFromIssuanceOfCommonLimitedPartnersUnits" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_NetCashProvidedByUsedInFinancingActivitiesContinuingOperations" xlink:to="us-gaap_ProceedsFromIssuanceOfCommonLimitedPartnersUnits" xlink:title="calculation: us-gaap_NetCashProvidedByUsedInFinancingActivitiesContinuingOperations to us-gaap_ProceedsFromIssuanceOfCommonLimitedPartnersUnits" use="optional" order="1.0" weight="1" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ProceedsFromLinesOfCredit" xlink:label="us-gaap_ProceedsFromLinesOfCredit" xlink:title="ProceedsFromLinesOfCredit" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_NetCashProvidedByUsedInFinancingActivitiesContinuingOperations" xlink:to="us-gaap_ProceedsFromLinesOfCredit" xlink:title="calculation: us-gaap_NetCashProvidedByUsedInFinancingActivitiesContinuingOperations to us-gaap_ProceedsFromLinesOfCredit" use="optional" order="2.0" weight="1" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_RepaymentsOfLinesOfCredit" xlink:label="us-gaap_RepaymentsOfLinesOfCredit" xlink:title="RepaymentsOfLinesOfCredit" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_NetCashProvidedByUsedInFinancingActivitiesContinuingOperations" xlink:to="us-gaap_RepaymentsOfLinesOfCredit" xlink:title="calculation: us-gaap_NetCashProvidedByUsedInFinancingActivitiesContinuingOperations to us-gaap_RepaymentsOfLinesOfCredit" use="optional" order="3.0" weight="-1" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ProceedsFromIssuanceOfLongTermDebt" xlink:label="us-gaap_ProceedsFromIssuanceOfLongTermDebt" xlink:title="ProceedsFromIssuanceOfLongTermDebt" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_NetCashProvidedByUsedInFinancingActivitiesContinuingOperations" xlink:to="us-gaap_ProceedsFromIssuanceOfLongTermDebt" xlink:title="calculation: us-gaap_NetCashProvidedByUsedInFinancingActivitiesContinuingOperations to us-gaap_ProceedsFromIssuanceOfLongTermDebt" use="optional" order="4.0" weight="1" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_RepaymentsOfLongTermDebt" xlink:label="us-gaap_RepaymentsOfLongTermDebt" xlink:title="RepaymentsOfLongTermDebt" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_NetCashProvidedByUsedInFinancingActivitiesContinuingOperations" xlink:to="us-gaap_RepaymentsOfLongTermDebt" xlink:title="calculation: us-gaap_NetCashProvidedByUsedInFinancingActivitiesContinuingOperations to us-gaap_RepaymentsOfLongTermDebt" use="optional" order="5.0" weight="-1" />
    <link:loc xlink:type="locator" xlink:href="mwe-20140630.xsd#mwe_PaymentsOfPremiumsOnRedemptionOfLongTermDebt" xlink:label="mwe_PaymentsOfPremiumsOnRedemptionOfLongTermDebt" xlink:title="PaymentsOfPremiumsOnRedemptionOfLongTermDebt" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_NetCashProvidedByUsedInFinancingActivitiesContinuingOperations" xlink:to="mwe_PaymentsOfPremiumsOnRedemptionOfLongTermDebt" xlink:title="calculation: us-gaap_NetCashProvidedByUsedInFinancingActivitiesContinuingOperations to mwe_PaymentsOfPremiumsOnRedemptionOfLongTermDebt" use="optional" order="6.0" weight="-1" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_PaymentOfFinancingAndStockIssuanceCosts" xlink:label="us-gaap_PaymentOfFinancingAndStockIssuanceCosts" xlink:title="PaymentOfFinancingAndStockIssuanceCosts" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_NetCashProvidedByUsedInFinancingActivitiesContinuingOperations" xlink:to="us-gaap_PaymentOfFinancingAndStockIssuanceCosts" xlink:title="calculation: us-gaap_NetCashProvidedByUsedInFinancingActivitiesContinuingOperations to us-gaap_PaymentOfFinancingAndStockIssuanceCosts" use="optional" order="7.0" weight="-1" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ProceedsFromMinorityShareholders" xlink:label="us-gaap_ProceedsFromMinorityShareholders" xlink:title="ProceedsFromMinorityShareholders" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_NetCashProvidedByUsedInFinancingActivitiesContinuingOperations" xlink:to="us-gaap_ProceedsFromMinorityShareholders" xlink:title="calculation: us-gaap_NetCashProvidedByUsedInFinancingActivitiesContinuingOperations to us-gaap_ProceedsFromMinorityShareholders" use="optional" order="10.0" weight="1" />
    <link:loc xlink:type="locator" xlink:href="mwe-20140630.xsd#mwe_PaymentOfLiability" xlink:label="mwe_PaymentOfLiability" xlink:title="PaymentOfLiability" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_NetCashProvidedByUsedInFinancingActivitiesContinuingOperations" xlink:to="mwe_PaymentOfLiability" xlink:title="calculation: us-gaap_NetCashProvidedByUsedInFinancingActivitiesContinuingOperations to mwe_PaymentOfLiability" use="optional" order="13.0" weight="-1" />
    <link:loc xlink:type="locator" xlink:href="mwe-20140630.xsd#mwe_ProceedsFromPaymentsForAdvancesToAffiliatesSubsidiariesAndHoldingCompanies" xlink:label="mwe_ProceedsFromPaymentsForAdvancesToAffiliatesSubsidiariesAndHoldingCompanies" xlink:title="ProceedsFromPaymentsForAdvancesToAffiliatesSubsidiariesAndHoldingCompanies" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_NetCashProvidedByUsedInFinancingActivitiesContinuingOperations" xlink:to="mwe_ProceedsFromPaymentsForAdvancesToAffiliatesSubsidiariesAndHoldingCompanies" xlink:title="calculation: us-gaap_NetCashProvidedByUsedInFinancingActivitiesContinuingOperations to mwe_ProceedsFromPaymentsForAdvancesToAffiliatesSubsidiariesAndHoldingCompanies" use="optional" order="8.0" weight="1" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ProceedsFromContributionsFromParent" xlink:label="us-gaap_ProceedsFromContributionsFromParent" xlink:title="ProceedsFromContributionsFromParent" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_NetCashProvidedByUsedInFinancingActivitiesContinuingOperations" xlink:to="us-gaap_ProceedsFromContributionsFromParent" xlink:title="calculation: us-gaap_NetCashProvidedByUsedInFinancingActivitiesContinuingOperations to us-gaap_ProceedsFromContributionsFromParent" use="optional" order="9.0" weight="1" />
    <link:loc xlink:type="locator" xlink:href="mwe-20140630.xsd#mwe_EmployeeServiceShareBasedCompensationCashFlowEffect" xlink:label="mwe_EmployeeServiceShareBasedCompensationCashFlowEffect" xlink:title="EmployeeServiceShareBasedCompensationCashFlowEffect" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_NetCashProvidedByUsedInFinancingActivitiesContinuingOperations" xlink:to="mwe_EmployeeServiceShareBasedCompensationCashFlowEffect" xlink:title="calculation: us-gaap_NetCashProvidedByUsedInFinancingActivitiesContinuingOperations to mwe_EmployeeServiceShareBasedCompensationCashFlowEffect" use="optional" order="11.0" weight="-1" />
    <link:loc xlink:type="locator" xlink:href="mwe-20140630.xsd#mwe_PaymentsOfDistributionsToCommonUnitholdersAndMinorityInterest" xlink:label="mwe_PaymentsOfDistributionsToCommonUnitholdersAndMinorityInterest" xlink:title="PaymentsOfDistributionsToCommonUnitholdersAndMinorityInterest" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_NetCashProvidedByUsedInFinancingActivitiesContinuingOperations" xlink:to="mwe_PaymentsOfDistributionsToCommonUnitholdersAndMinorityInterest" xlink:title="calculation: us-gaap_NetCashProvidedByUsedInFinancingActivitiesContinuingOperations to mwe_PaymentsOfDistributionsToCommonUnitholdersAndMinorityInterest" use="optional" order="12.0" weight="-1" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_IncreaseDecreaseInDueFromAffiliatesCurrent" xlink:label="us-gaap_IncreaseDecreaseInDueFromAffiliatesCurrent" xlink:title="IncreaseDecreaseInDueFromAffiliatesCurrent" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_NetCashProvidedByUsedInFinancingActivitiesContinuingOperations" xlink:to="us-gaap_IncreaseDecreaseInDueFromAffiliatesCurrent" xlink:title="calculation: us-gaap_NetCashProvidedByUsedInFinancingActivitiesContinuingOperations to us-gaap_IncreaseDecreaseInDueFromAffiliatesCurrent" use="optional" order="14.0" weight="-1" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_NetCashProvidedByUsedInInvestingActivitiesContinuingOperations" xlink:label="us-gaap_NetCashProvidedByUsedInInvestingActivitiesContinuingOperations" xlink:title="NetCashProvidedByUsedInInvestingActivitiesContinuingOperations" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_NetCashProvidedByUsedInContinuingOperations" xlink:to="us-gaap_NetCashProvidedByUsedInInvestingActivitiesContinuingOperations" xlink:title="calculation: us-gaap_NetCashProvidedByUsedInContinuingOperations to us-gaap_NetCashProvidedByUsedInInvestingActivitiesContinuingOperations" order="3.0" weight="1" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_IncreaseDecreaseInRestrictedCash" xlink:label="us-gaap_IncreaseDecreaseInRestrictedCash" xlink:title="IncreaseDecreaseInRestrictedCash" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_NetCashProvidedByUsedInInvestingActivitiesContinuingOperations" xlink:to="us-gaap_IncreaseDecreaseInRestrictedCash" xlink:title="calculation: us-gaap_NetCashProvidedByUsedInInvestingActivitiesContinuingOperations to us-gaap_IncreaseDecreaseInRestrictedCash" use="optional" order="1.0" weight="-1" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_PaymentsToAcquirePropertyPlantAndEquipment" xlink:label="us-gaap_PaymentsToAcquirePropertyPlantAndEquipment" xlink:title="PaymentsToAcquirePropertyPlantAndEquipment" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_NetCashProvidedByUsedInInvestingActivitiesContinuingOperations" xlink:to="us-gaap_PaymentsToAcquirePropertyPlantAndEquipment" xlink:title="calculation: us-gaap_NetCashProvidedByUsedInInvestingActivitiesContinuingOperations to us-gaap_PaymentsToAcquirePropertyPlantAndEquipment" use="optional" order="2.0" weight="-1" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_PaymentsToAcquireEquityMethodInvestments" xlink:label="us-gaap_PaymentsToAcquireEquityMethodInvestments" xlink:title="PaymentsToAcquireEquityMethodInvestments" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_NetCashProvidedByUsedInInvestingActivitiesContinuingOperations" xlink:to="us-gaap_PaymentsToAcquireEquityMethodInvestments" xlink:title="calculation: us-gaap_NetCashProvidedByUsedInInvestingActivitiesContinuingOperations to us-gaap_PaymentsToAcquireEquityMethodInvestments" use="optional" order="3.0" weight="-1" />
    <link:loc xlink:type="locator" xlink:href="mwe-20140630.xsd#mwe_PaymentsToAcquireInterestInSubsidiaries" xlink:label="mwe_PaymentsToAcquireInterestInSubsidiaries" xlink:title="PaymentsToAcquireInterestInSubsidiaries" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_NetCashProvidedByUsedInInvestingActivitiesContinuingOperations" xlink:to="mwe_PaymentsToAcquireInterestInSubsidiaries" xlink:title="calculation: us-gaap_NetCashProvidedByUsedInInvestingActivitiesContinuingOperations to mwe_PaymentsToAcquireInterestInSubsidiaries" use="optional" order="4.0" weight="-1" />
    <link:loc xlink:type="locator" xlink:href="mwe-20140630.xsd#mwe_ConsolidatedAffiliateDividendsOrDistributions" xlink:label="mwe_ConsolidatedAffiliateDividendsOrDistributions" xlink:title="ConsolidatedAffiliateDividendsOrDistributions" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_NetCashProvidedByUsedInInvestingActivitiesContinuingOperations" xlink:to="mwe_ConsolidatedAffiliateDividendsOrDistributions" xlink:title="calculation: us-gaap_NetCashProvidedByUsedInInvestingActivitiesContinuingOperations to mwe_ConsolidatedAffiliateDividendsOrDistributions" use="optional" order="5.0" weight="1" />
    <link:loc xlink:type="locator" xlink:href="mwe-20140630.xsd#mwe_CollectionOfPaymentsToAcquireIntercompanyNotesNet" xlink:label="mwe_CollectionOfPaymentsToAcquireIntercompanyNotesNet" xlink:title="CollectionOfPaymentsToAcquireIntercompanyNotesNet" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_NetCashProvidedByUsedInInvestingActivitiesContinuingOperations" xlink:to="mwe_CollectionOfPaymentsToAcquireIntercompanyNotesNet" xlink:title="calculation: us-gaap_NetCashProvidedByUsedInInvestingActivitiesContinuingOperations to mwe_CollectionOfPaymentsToAcquireIntercompanyNotesNet" use="optional" order="6.0" weight="1" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_PaymentsToAcquireBusinessesNetOfCashAcquired" xlink:label="us-gaap_PaymentsToAcquireBusinessesNetOfCashAcquired" xlink:title="PaymentsToAcquireBusinessesNetOfCashAcquired" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_NetCashProvidedByUsedInInvestingActivitiesContinuingOperations" xlink:to="us-gaap_PaymentsToAcquireBusinessesNetOfCashAcquired" xlink:title="calculation: us-gaap_NetCashProvidedByUsedInInvestingActivitiesContinuingOperations to us-gaap_PaymentsToAcquireBusinessesNetOfCashAcquired" use="optional" order="7.0" weight="-1" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ProceedsFromSaleOfPropertyPlantAndEquipment" xlink:label="us-gaap_ProceedsFromSaleOfPropertyPlantAndEquipment" xlink:title="ProceedsFromSaleOfPropertyPlantAndEquipment" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_NetCashProvidedByUsedInInvestingActivitiesContinuingOperations" xlink:to="us-gaap_ProceedsFromSaleOfPropertyPlantAndEquipment" xlink:title="calculation: us-gaap_NetCashProvidedByUsedInInvestingActivitiesContinuingOperations to us-gaap_ProceedsFromSaleOfPropertyPlantAndEquipment" use="optional" order="8.0" weight="1" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_ProceedsFromSaleOfEquityMethodInvestments" xlink:label="us-gaap_ProceedsFromSaleOfEquityMethodInvestments" xlink:title="ProceedsFromSaleOfEquityMethodInvestments" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_NetCashProvidedByUsedInInvestingActivitiesContinuingOperations" xlink:to="us-gaap_ProceedsFromSaleOfEquityMethodInvestments" xlink:title="calculation: us-gaap_NetCashProvidedByUsedInInvestingActivitiesContinuingOperations to us-gaap_ProceedsFromSaleOfEquityMethodInvestments" use="optional" order="9.0" weight="1" />
  </link:calculationLink>
  <link:calculationLink xlink:type="extended" xlink:role="http://www.markwest.com/role/DisclosureSegmentInformationDetails5">
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_Assets" xlink:label="us-gaap_Assets" xlink:title="Assets" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_EquityMethodInvestments" xlink:label="us-gaap_EquityMethodInvestments" xlink:title="EquityMethodInvestments" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_Assets" xlink:to="us-gaap_EquityMethodInvestments" xlink:title="calculation: us-gaap_Assets to us-gaap_EquityMethodInvestments" use="optional" order="3.0" weight="1" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_CashAndCashEquivalentsAtCarryingValue" xlink:label="us-gaap_CashAndCashEquivalentsAtCarryingValue" xlink:title="CashAndCashEquivalentsAtCarryingValue" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_Assets" xlink:to="us-gaap_CashAndCashEquivalentsAtCarryingValue" xlink:title="calculation: us-gaap_Assets to us-gaap_CashAndCashEquivalentsAtCarryingValue" use="optional" order="1.0" weight="1" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_DerivativeAssets" xlink:label="us-gaap_DerivativeAssets" xlink:title="DerivativeAssets" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_Assets" xlink:to="us-gaap_DerivativeAssets" xlink:title="calculation: us-gaap_Assets to us-gaap_DerivativeAssets" use="optional" order="2.0" weight="1" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_AccountsReceivableRelatedPartiesCurrent" xlink:label="us-gaap_AccountsReceivableRelatedPartiesCurrent" xlink:title="AccountsReceivableRelatedPartiesCurrent" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_Assets" xlink:to="us-gaap_AccountsReceivableRelatedPartiesCurrent" xlink:title="calculation: us-gaap_Assets to us-gaap_AccountsReceivableRelatedPartiesCurrent" use="optional" order="4.0" weight="1" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_OtherAssets" xlink:label="us-gaap_OtherAssets" xlink:title="OtherAssets" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_Assets" xlink:to="us-gaap_OtherAssets" xlink:title="calculation: us-gaap_Assets to us-gaap_OtherAssets" use="optional" order="5.0" weight="1" />
  </link:calculationLink>
  <link:calculationLink xlink:type="extended" xlink:role="http://www.markwest.com/role/DisclosureSegmentInformationDetails2">
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_Revenues" xlink:label="us-gaap_Revenues" xlink:title="Revenues" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_GasGatheringTransportationMarketingAndProcessingRevenue" xlink:label="us-gaap_GasGatheringTransportationMarketingAndProcessingRevenue" xlink:title="GasGatheringTransportationMarketingAndProcessingRevenue" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_Revenues" xlink:to="us-gaap_GasGatheringTransportationMarketingAndProcessingRevenue" xlink:title="calculation: us-gaap_Revenues to us-gaap_GasGatheringTransportationMarketingAndProcessingRevenue" use="optional" order="1.0" weight="1" />
    <link:loc xlink:type="locator" xlink:href="mwe-20140630.xsd#mwe_GainLossOnPriceRiskDerivativeInstrumentsNotDesignatedAsHedgingInstrumentsRelatedToRevenue" xlink:label="mwe_GainLossOnPriceRiskDerivativeInstrumentsNotDesignatedAsHedgingInstrumentsRelatedToRevenue" xlink:title="GainLossOnPriceRiskDerivativeInstrumentsNotDesignatedAsHedgingInstrumentsRelatedToRevenue" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_Revenues" xlink:to="mwe_GainLossOnPriceRiskDerivativeInstrumentsNotDesignatedAsHedgingInstrumentsRelatedToRevenue" xlink:title="calculation: us-gaap_Revenues to mwe_GainLossOnPriceRiskDerivativeInstrumentsNotDesignatedAsHedgingInstrumentsRelatedToRevenue" use="optional" order="2.0" weight="1" />
    <link:loc xlink:type="locator" xlink:href="mwe-20140630.xsd#mwe_RevenueAdjustmentForUnconsolidatedAffiliate" xlink:label="mwe_RevenueAdjustmentForUnconsolidatedAffiliate" xlink:title="RevenueAdjustmentForUnconsolidatedAffiliate" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_Revenues" xlink:to="mwe_RevenueAdjustmentForUnconsolidatedAffiliate" xlink:title="calculation: us-gaap_Revenues to mwe_RevenueAdjustmentForUnconsolidatedAffiliate" use="optional" order="3.0" weight="-1" />
    <link:loc xlink:type="locator" xlink:href="mwe-20140630.xsd#mwe_DeferredRevenueAdjustment" xlink:label="mwe_DeferredRevenueAdjustment" xlink:title="DeferredRevenueAdjustment" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_Revenues" xlink:to="mwe_DeferredRevenueAdjustment" xlink:title="calculation: us-gaap_Revenues to mwe_DeferredRevenueAdjustment" use="optional" order="4.0" weight="-1" />
  </link:calculationLink>
  <link:calculationLink xlink:type="extended" xlink:role="http://www.markwest.com/role/DisclosureDerivativeFinancialInstrumentsDetails4">
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_DerivativeInstrumentsNotDesignatedAsHedgingInstrumentsGainLossNet" xlink:label="us-gaap_DerivativeInstrumentsNotDesignatedAsHedgingInstrumentsGainLossNet" xlink:title="DerivativeInstrumentsNotDesignatedAsHedgingInstrumentsGainLossNet" />
    <link:loc xlink:type="locator" xlink:href="mwe-20140630.xsd#mwe_RealizedGainLossOnDerivativeInstrumentsNotDesignatedAsHedgingInstruments" xlink:label="mwe_RealizedGainLossOnDerivativeInstrumentsNotDesignatedAsHedgingInstruments" xlink:title="RealizedGainLossOnDerivativeInstrumentsNotDesignatedAsHedgingInstruments" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_DerivativeInstrumentsNotDesignatedAsHedgingInstrumentsGainLossNet" xlink:to="mwe_RealizedGainLossOnDerivativeInstrumentsNotDesignatedAsHedgingInstruments" xlink:title="calculation: us-gaap_DerivativeInstrumentsNotDesignatedAsHedgingInstrumentsGainLossNet to mwe_RealizedGainLossOnDerivativeInstrumentsNotDesignatedAsHedgingInstruments" use="optional" order="1.0" weight="1" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_UnrealizedGainLossOnDerivatives" xlink:label="us-gaap_UnrealizedGainLossOnDerivatives" xlink:title="UnrealizedGainLossOnDerivatives" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_DerivativeInstrumentsNotDesignatedAsHedgingInstrumentsGainLossNet" xlink:to="us-gaap_UnrealizedGainLossOnDerivatives" xlink:title="calculation: us-gaap_DerivativeInstrumentsNotDesignatedAsHedgingInstrumentsGainLossNet to us-gaap_UnrealizedGainLossOnDerivatives" use="optional" order="2.0" weight="1" />
  </link:calculationLink>
  <link:calculationLink xlink:type="extended" xlink:role="http://www.markwest.com/role/DisclosureBusinessCombinationsDetails">
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredGoodwillAndLiabilitiesAssumedNet" xlink:label="us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredGoodwillAndLiabilitiesAssumedNet" xlink:title="BusinessCombinationRecognizedIdentifiableAssetsAcquiredGoodwillAndLiabilitiesAssumedNet" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedPropertyPlantAndEquipment" xlink:label="us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedPropertyPlantAndEquipment" xlink:title="BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedPropertyPlantAndEquipment" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredGoodwillAndLiabilitiesAssumedNet" xlink:to="us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedPropertyPlantAndEquipment" xlink:title="calculation: us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredGoodwillAndLiabilitiesAssumedNet to us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedPropertyPlantAndEquipment" use="optional" order="1.0" weight="1" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_Goodwill" xlink:label="us-gaap_Goodwill" xlink:title="Goodwill" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredGoodwillAndLiabilitiesAssumedNet" xlink:to="us-gaap_Goodwill" xlink:title="calculation: us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredGoodwillAndLiabilitiesAssumedNet to us-gaap_Goodwill" use="optional" order="2.0" weight="1" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedIntangibles" xlink:label="us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedIntangibles" xlink:title="BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedIntangibles" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredGoodwillAndLiabilitiesAssumedNet" xlink:to="us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedIntangibles" xlink:title="calculation: us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredGoodwillAndLiabilitiesAssumedNet to us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedIntangibles" use="optional" order="3.0" weight="1" />
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2013/elts/us-gaap-2013-01-31.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentLiabilitiesAccountsPayable" xlink:label="us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentLiabilitiesAccountsPayable" xlink:title="BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentLiabilitiesAccountsPayable" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredGoodwillAndLiabilitiesAssumedNet" xlink:to="us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentLiabilitiesAccountsPayable" xlink:title="calculation: us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredGoodwillAndLiabilitiesAssumedNet to us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentLiabilitiesAccountsPayable" use="optional" order="4.0" weight="-1" />
  </link:calculationLink>
</link:linkbase>


