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  <xs:element name="ScheduleOfLinesOfCreditAbstract" type="xbrli:stringItemType" abstract="true" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item" id="msex_ScheduleOfLinesOfCreditAbstract"/>
  <xs:element name="ScheduleOfOperatingRevenueAbstract" type="xbrli:stringItemType" abstract="true" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item" id="msex_ScheduleOfOperatingRevenueAbstract"/>
  <xs:element name="UnlabeledAbstract" type="xbrli:stringItemType" abstract="true" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item" id="msex_UnlabeledAbstract"/>
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  <xs:element name="EarningsPerShareOfCommonStockAbstract" type="xbrli:stringItemType" abstract="true" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item" id="msex_EarningsPerShareOfCommonStockAbstract"/>
  <xs:element name="UnlabeledAbstract12" type="xbrli:stringItemType" abstract="true" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item" id="msex_UnlabeledAbstract12"/>
  <xs:element name="AverageNumberOfAbstract" type="xbrli:stringItemType" abstract="true" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item" id="msex_AverageNumberOfAbstract"/>
  <xs:element name="CommonSharesOutstandingAbstract" type="xbrli:stringItemType" abstract="true" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item" id="msex_CommonSharesOutstandingAbstract"/>
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  <xs:element name="CapitalizationAndLiabilitiesAbstract" type="xbrli:stringItemType" abstract="true" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item" id="msex_CapitalizationAndLiabilitiesAbstract"/>
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  <xs:element name="CumulativePreferredStockNoParValueAbstract" type="xbrli:stringItemType" abstract="true" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item" id="msex_CumulativePreferredStockNoParValueAbstract"/>
  <xs:element name="ConvertibleAbstract" type="xbrli:stringItemType" abstract="true" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item" id="msex_ConvertibleAbstract"/>
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  <xs:element name="ForTheNineMonthsEndedSeptember302022Abstract" type="xbrli:stringItemType" abstract="true" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item" id="msex_ForTheNineMonthsEndedSeptember302022Abstract"/>
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  <xs:element name="EmployeeBenefitPlans" type="xbrli:monetaryItemType" abstract="false" xbrli:periodType="instant" xbrli:balance="debit" nillable="true" substitutionGroup="xbrli:item" id="msex_EmployeeBenefitPlans"/>
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  <xs:element name="ConstructionAdvances" type="xbrli:monetaryItemType" abstract="false" xbrli:periodType="instant" xbrli:balance="credit" nillable="true" substitutionGroup="xbrli:item" id="msex_ConstructionAdvances"/>
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  <xs:element name="MiddlesexPresidentAndChiefExecutiveOfficerRetirementAnnouncementPolicyTextBlock" type="dtr:textBlockItemType" abstract="false" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item" id="msex_MiddlesexPresidentAndChiefExecutiveOfficerRetirementAnnouncementPolicyTextBlock"/>
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  <xs:element name="EarningsPerShareDetailsScheduleofEarningsPerShareTable" type="xbrli:stringItemType" abstract="true" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrldt:hypercubeItem" id="msex_EarningsPerShareDetailsScheduleofEarningsPerShareTable"/>
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  <xs:element name="PercentageOfDiscountPurchaseOfCommonStockInInvestmentPlan" type="dtr:percentItemType" abstract="false" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item" id="msex_PercentageOfDiscountPurchaseOfCommonStockInInvestmentPlan"/>
  <xs:element name="NumberOfSharesOfferingForDiscount" type="xbrli:sharesItemType" abstract="false" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item" id="msex_NumberOfSharesOfferingForDiscount"/>
  <xs:element name="MarketInterestRate" type="dtr:percentItemType" abstract="false" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item" id="msex_MarketInterestRate"/>
  <xs:element name="PercentageOfPrincipalWithStatedInterestRate" type="dtr:percentItemType" abstract="false" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item" id="msex_PercentageOfPrincipalWithStatedInterestRate"/>
  <xs:element name="MaturityDate" type="xbrli:stringItemType" abstract="false" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item" id="msex_MaturityDate"/>
  <xs:element name="BorrowedLoan" type="xbrli:monetaryItemType" abstract="false" xbrli:periodType="duration" xbrli:balance="debit" nillable="true" substitutionGroup="xbrli:item" id="msex_BorrowedLoan"/>
  <xs:element name="ProgramLoanAmount" type="xbrli:monetaryItemType" abstract="false" xbrli:periodType="duration" xbrli:balance="debit" nillable="true" substitutionGroup="xbrli:item" id="msex_ProgramLoanAmount"/>
  <xs:element name="CustomerAdvancesForConstructionWork" type="xbrli:monetaryItemType" abstract="false" xbrli:periodType="instant" xbrli:balance="credit" nillable="true" substitutionGroup="xbrli:item" id="msex_CustomerAdvancesForConstructionWork"/>
  <xs:element name="ConstructionLoanMaximumBorrowingCapacity" type="xbrli:monetaryItemType" abstract="false" xbrli:periodType="instant" xbrli:balance="credit" nillable="true" substitutionGroup="xbrli:item" id="msex_ConstructionLoanMaximumBorrowingCapacity"/>
  <xs:element name="EarningsPerShareDetailsTable" type="xbrli:stringItemType" abstract="true" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrldt:hypercubeItem" id="msex_EarningsPerShareDetailsTable"/>
  <xs:element name="BusinessSegmentDataDetailsTable" type="xbrli:stringItemType" abstract="true" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrldt:hypercubeItem" id="msex_BusinessSegmentDataDetailsTable"/>
  <xs:element name="ShortTermBorrowingsDetailsTable" type="xbrli:stringItemType" abstract="true" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrldt:hypercubeItem" id="msex_ShortTermBorrowingsDetailsTable"/>
  <xs:element name="OutstandingMaturityDate" type="xbrli:stringItemType" abstract="false" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item" id="msex_OutstandingMaturityDate"/>
  <xs:element name="CommitmentsandContingentLiabilitiesDetailsTable" type="xbrli:stringItemType" abstract="true" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrldt:hypercubeItem" id="msex_CommitmentsandContingentLiabilitiesDetailsTable"/>
  <xs:element name="LongtermPurchaseCommitmentExpirationDate" type="xbrli:dateItemType" abstract="false" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item" id="msex_LongtermPurchaseCommitmentExpirationDate"/>
  <xs:element name="EstimatedIncrementalBorrowingRate" type="dtr:percentItemType" abstract="false" xbrli:periodType="instant" nillable="true" substitutionGroup="xbrli:item" id="msex_EstimatedIncrementalBorrowingRate"/>
  <xs:element name="BudgetedConstructionCost" type="xbrli:monetaryItemType" abstract="false" xbrli:periodType="duration" xbrli:balance="debit" nillable="true" substitutionGroup="xbrli:item" id="msex_BudgetedConstructionCost"/>
  <xs:element name="Estimatedobligationexpenditure" type="xbrli:monetaryItemType" abstract="false" xbrli:periodType="duration" xbrli:balance="credit" nillable="true" substitutionGroup="xbrli:item" id="msex_Estimatedobligationexpenditure"/>
  <xs:element name="EmployeeBenefitPlansDetailsTable" type="xbrli:stringItemType" abstract="true" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrldt:hypercubeItem" id="msex_EmployeeBenefitPlansDetailsTable"/>
  <xs:element name="AmortizingSecuredNoteMember" type="dtr:domainItemType" abstract="true" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item" id="msex_AmortizingSecuredNoteMember"/>
  <xs:element name="AmortizingSecuredNotesDue20282046Member" type="dtr:domainItemType" abstract="true" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item" id="msex_AmortizingSecuredNotesDue20282046Member"/>
  <xs:element name="AnnualBenefitsPlanMember" type="dtr:domainItemType" abstract="true" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item" id="msex_AnnualBenefitsPlanMember"/>
  <xs:element name="BankOfAmericaMember" type="dtr:domainItemType" abstract="true" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item" id="msex_BankOfAmericaMember"/>
  <xs:element name="CoBankMember" type="dtr:domainItemType" abstract="true" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item" id="msex_CoBankMember"/>
  <xs:element name="DelawareStateRevolvingFundMember" type="dtr:domainItemType" abstract="true" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item" id="msex_DelawareStateRevolvingFundMember"/>
  <xs:element name="FMBMember" type="dtr:domainItemType" abstract="true" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item" id="msex_FMBMember"/>
  <xs:element name="FirstMortgageBondsDue20232059Member" type="dtr:domainItemType" abstract="true" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item" id="msex_FirstMortgageBondsDue20232059Member"/>
  <xs:element name="FirstMortgageOne1Member" type="dtr:domainItemType" abstract="true" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item" id="msex_FirstMortgageOne1Member"/>
  <xs:element name="IncomeMember" type="dtr:domainItemType" abstract="true" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item" id="msex_IncomeMember"/>
  <xs:element name="InterSegmentEliminationMember" type="dtr:domainItemType" abstract="true" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item" id="msex_InterSegmentEliminationMember"/>
  <xs:element name="MiddlesexWaterCompanyMember" type="dtr:domainItemType" abstract="true" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item" id="msex_MiddlesexWaterCompanyMember"/>
  <xs:element name="MiddlesexWaterMember" type="dtr:domainItemType" abstract="true" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item" id="msex_MiddlesexWaterMember"/>
  <xs:element name="NewJerseyBoardOfPublicUtilitiesMember" type="dtr:domainItemType" abstract="true" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item" id="msex_NewJerseyBoardOfPublicUtilitiesMember"/>
  <xs:element name="NewJerseyInfrastructureBankMember" type="dtr:domainItemType" abstract="true" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item" id="msex_NewJerseyInfrastructureBankMember"/>
  <xs:element name="NonRegulatedMember" type="dtr:domainItemType" abstract="true" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item" id="msex_NonRegulatedMember"/>
  <xs:element name="NonredeemablePreferredStock1Member" type="dtr:domainItemType" abstract="true" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item" id="msex_NonredeemablePreferredStock1Member"/>
  <xs:element name="PinelandsMember" type="dtr:domainItemType" abstract="true" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item" id="msex_PinelandsMember"/>
  <xs:element name="PinelandsWastewaterMember" type="dtr:domainItemType" abstract="true" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item" id="msex_PinelandsWastewaterMember"/>
  <xs:element name="PinelandsWaterMember" type="dtr:domainItemType" abstract="true" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item" id="msex_PinelandsWaterMember"/>
  <xs:element name="PncBankMember" type="dtr:domainItemType" abstract="true" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item" id="msex_PncBankMember"/>
  <xs:element name="PrivatePlacementLoanMember" type="dtr:domainItemType" abstract="true" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item" id="msex_PrivatePlacementLoanMember"/>
  <xs:element name="PurchaseCommitment1Member" type="dtr:domainItemType" abstract="true" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item" id="msex_PurchaseCommitment1Member"/>
  <xs:element name="PurchaseCommitment2Member" type="dtr:domainItemType" abstract="true" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item" id="msex_PurchaseCommitment2Member"/>
  <xs:element name="RegulatedMember" type="dtr:domainItemType" abstract="true" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item" id="msex_RegulatedMember"/>
  <xs:element name="SharesMember" type="dtr:domainItemType" abstract="true" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item" id="msex_SharesMember"/>
  <xs:element name="ShorttermBorrowingsMember" type="dtr:domainItemType" abstract="true" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item" id="msex_ShorttermBorrowingsMember"/>
  <xs:element name="StateRevolvingTrustNotesDue20252044Member" type="dtr:domainItemType" abstract="true" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item" id="msex_StateRevolvingTrustNotesDue20252044Member"/>
  <xs:element name="StateRevolvingTrustNotesOneMember" type="dtr:domainItemType" abstract="true" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item" id="msex_StateRevolvingTrustNotesOneMember"/>
  <xs:element name="TidewaterMember" type="dtr:domainItemType" abstract="true" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item" id="msex_TidewaterMember"/>
  <xs:element name="CashPaidDuringTheYearForAbstract" type="xbrli:stringItemType" abstract="true" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item" id="msex_CashPaidDuringTheYearForAbstract"/>
  <xs:element name="DocumentAndEntityInformationAbstract" type="xbrli:stringItemType" abstract="true" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item" id="msex_DocumentAndEntityInformationAbstract"/>
</xs:schema>
