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Washington water hardness, by utility.

1,481 Washington utilities serving 7.9 million people as they report it, from the state’s own results. Hardness is the calcium and magnesium in water; EPA sets no limit for it.

The short answer

177 utilities serving 4 million people have water in more than one band. Among those in one band, soft water reaches the most people: 412 utilities serving 2.5 million.

The largest, Seattle Public Utilities, is soft, typically 26 mg/L (1.5 grains per gallon).

Very hard

Above 180 mg/L (10.5 grains per gallon). 196 utilities serving 151,884 people; the 25 largest are here.

Washington utilities: very hard water
UtilityBased inServesHardness, mg/LGrains per gallon
City of WenatcheeWenatchee43,69024514.3
City of Quincy Water DepartmentQuincy8,41521012.3
Spo Co Water Dist 3 Sys 4Spokane6,23319011.1
Cashmere Water DepartmentCashmere5,81522913.4
Benton City WaterBenton City5,62628516.7
Colville Water DepartmentColville4,94527015.8
City of OmakOmak4,94031018.1
Town of CoupevilleCoupeville4,14230017.5
City of Okanogan Water DepartmentOkanogan3,81737021.6
City of ZillahZillah3,51821812.7
City of OrovilleOroville3,25624414.3
City of Rock Island Water DeptRock Island3,22629017
Kettle Falls Water DeptKettle Falls2,69818410.8
Malaga Water DistrictMalaga2,47827315.9
Tonasket Water SystemTonasket2,39822913.4
Ione Water DeptIon2,39524814.5
City of BridgeportBridgeport2,21427215.9
City of EntiatEntiat1,73018510.8
Sunland Estates Homeowners AssnQuincy1,48023313.6
Carlsborg Lud 10 12 13 14Carlsborg1,34921212.4
Freeland Water and Sewer DistrictFreeland1,26419911.6
Stevens Co PUD - Waitts LakeLoon Lake1,21635020.5
Fisherman Bay Water AssociationLopez Island1,19529317.1
Weiler - Martin Tracts Water AssnQuincy1,16321512.6
Pateros Water DepartmentPateros1,14925815.1
All 196 with very hard water

Hard

121 to 180 mg/L (7.1 to 10.5 grains per gallon). 195 utilities serving 139,488 people; the 25 largest are here.

Washington utilities: hard water
UtilityBased inServesHardness, mg/LGrains per gallon
City of Battle Ground Water DeptBattle Ground30,2371357.9
Spo Co Water Dist 3 Sys 1Spokane19,03517310.1
City of Airway HeightsAirway9,48917310.1
City of MiltonMilton8,0781357.9
City of FircrestFircrest7,9271408.2
Orchard Avenue Irrigation Dist 6Spokane4,3301609.4
City of BrewsterBrewster3,8431659.6
City of Colfax Water DepartmentColfax3,5071468.5
Lake Forest Park Water DistrictLake Forest Park3,1711569.1
Sumas Water DeptSumas2,1571619.4
City of MabtonMabton2,1501287.5
Deer Creek Water Assoc.Lynden2,00017410.2
City of MillwoodSpokane1,9251317.6
Summit View Water SystemKennewick1,8691458.5
Moab Irrigation Dist #20Newman Lake1,7901709.9
Glenhaven Lakes ClubSedro Woolley1,7801378
Evergreen Clallam County PUD 1Carlsborg1,69417810.4
City of RepublicRepublic1,6731217.1
Concrete UtilitiesMT Vernon1,2341227.1
Basin Water Sources IncCle Elum1,1581669.7
Sunshine AcresTacoma1,0741227.1
Camano Co - Op Water & Power CoMT Vernon1,07117310.1
Sunserra at Crescent BarQuincy1,0001468.5
Lake LawrenceTacoma9141357.9
Solmar WaterSequim8951508.8
All 195 with hard water

Moderately hard

61 to 120 mg/L (3.6 to 7 grains per gallon). 501 utilities serving 1 million people; the 25 largest are here.

Washington utilities: moderately hard water
UtilityBased inServesHardness, mg/LGrains per gallon
City of Redmond Water SystemRedmond163,335945.5
Pasco Water DepartmentPasco115,102744.3
Sno PUD 1 - Lake StevensEverett67,710824.8
Longview Water DepartmentLongview57,6171106.4
Bonney Lake Water Department CityBuckley43,3711146.7
City of Pullman Water DepartmentPullman31,3151136.6
City of Mercer IslandMercer Island31,057834.9
East Wenatchee Water DistrictEast Wenatchee26,519724.2
Vera Water & PowerSpokane Valley24,692844.9
North Perry Ave Water DistrictBremerton24,402945.5
Ridgefield Public WorksRidgefield21,225975.7
King County Water District No 90Renton20,100754.4
City of PoulsboPoulsbo18,400683.9
Olympic View Water & Sewer DistrictEdmonds17,7841106.4
City of YelmYelm17,355663.9
Naval Base Kitsap at BangorSilverdale16,828724.2
City of SumnerSumner16,438985.7
Fruitland Mutual Water CompanyPuyallup15,3131036
City of SheltonShelton15,273623.6
City of Dupont Water SystemDupont13,141684
Skyway Water & SewerSeattle12,0361126.5
City of WoodlandWoodland10,640875.1
NE Sammamish Sewer & Water DistrictSammamish9,702694
Mountain View - Edgewood Water CoEdgewood9,6801026
North Beach WaterOcean Park8,093694
All 501 with moderately hard water

Soft

Up to 60 mg/L (3.5 grains per gallon). 412 utilities serving 2.5 million people; the 25 largest are here.

Washington utilities: soft water
UtilityBased inServesHardness, mg/LGrains per gallon
Seattle Public UtilitiesSeattle1,161,961261.5
City of Everett Public Works Dept.Everett215,774120.7
City of Bellingham - Water DivisionBellingham141,127201.2
City of OlympiaOlympia126,966523
City of Yakima Water DivisionYakima112,858412.4
Skagit County PUD 1 Judy ResMount Vernon111,415221.3
Covington Water DistrictKent56,172251.5
City of TumwaterTumwater51,924573.3
Jblm LewisJoint Base Lewis - McChord35,414502.9
Camas Municipal Water Sewer SystemCamas31,794472.7
City of Port AngelesPort Angeles28,067472.7
City of AnacortesMount Vernon25,109221.3
City of AberdeenAberdeen22,867221.3
City of WashougalWashougal21,441301.8
Lynden Water DepartmentLynden20,062472.7
City of Port TownsendPort Townsend17,053452.7
City of KelsoKelso15,775251.5
Chehalis Water DepartmentChehalis11,718502.9
Hoquiam Water DepartmentHoquiam11,456261.5
City of LeavenworthLeavenworth11,041251.5
Lwwsd - South Shore Water SystemBellingham10,028201.2
Othello Water DepartmentOthello8,755211.3
City of ProsserProsser8,030513
City of KalamaKalama8,020171
Lake Chelan Reclamation DistrictManson6,798211.2
All 412 with soft water

Varies

Water in more than one band, depending on where or when it was sampled: each is given as its range, softest to hardest, and its report says more. 177 utilities serving 4 million people; the 25 largest are here.

Washington utilities: varies water
UtilityBased inServesHardness, mg/LGrains per gallon
City of Tacoma Water DivisionTacoma446,24512 to 1970.7 to 11.5
City of VancouverVancouver373,04755 to 1303.2 to 7.6
City of SpokaneSpokane346,13887 to 1745.1 to 10.2
City of BellevueBellevue321,34947 to 792.7 to 4.6
Kent Water DepartmentKent166,42116 to 1200.9 to 7
Clark Public UtilitiesVancouver153,52625 to 1401.5 to 8.2
Lakehaven Water and Sewer DistrictFederal Way148,809100 to 1465.8 to 8.5
City of KennewickKennewick118,16464 to 2123.7 to 12.4
City of RentonRenton108,09148 to 1252.8 to 7.3
City of AuburnAuburn107,65561 to 1283.6 to 7.5
City of RichlandRichland106,49970 to 2664.1 to 15.6
Lacey Water DepartmentLacey105,17832 to 1201.9 to 7
Highline Water DistrictKent100,17070 to 1664.1 to 9.7
City of PuyallupPuyallup94,52048 to 1062.8 to 6.2
Marysville UtilitiesMarysville88,58258 to 763.4 to 4.5
Lakewood Water DistrictLakewood82,42539 to 982.3 to 5.7
Sammamish Plateau Water & SewerSammamish79,36251 to 953 to 5.6
City of BremertonBremerton72,95133 to 1201.9 to 7
SouthwoodTacoma64,15530 to 1011.8 to 5.9
Issaquah Water SystemIssaquah43,58458 to 933.4 to 5.4
Walla Walla Water DivisionWalla Walla42,95928 to 701.6 to 4.1
Nob Hill Water AssociationYakima38,05024 to 671.4 to 3.9
Firgrove Mutual IncPuyallup36,16844 to 1022.6 to 6
Silverdale Water Dist 16Silverdale35,16340 to 982.3 to 5.7
Parkland Light & Water CompanyTacoma33,77548 to 832.8 to 4.9
All 177 whose water varies

Source: Washington State Department of Health, Office of Drinking Water, 1,479 utilities, results from Jan. 7, 2020 to Sept. 22, 2026, read Oct. 10, 2026. Each sampling point is taken at its median; a figure is typical where every point falls in one band.

Also: 2 utilities’ own water quality reports, read by hand, each named on the utility’s page.

Bands are the U.S. Geological Survey’s, at 17.1 mg/L to the grain. People served is what each utility reports; where one sells water to another, the same people can be counted twice. How hardness is measured here.

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