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Ohio utilities with very hard water.

Above 180 mg/L (10.5 grains per gallon). 26 utilities serving 241,670 people as they report it, largest first.

All 26, by people served

Ohio utilities with very hard water, 1 to 26
UtilityBased inServesHardness, mg/LGrains per gallon
Aqua Ohio - Massillon PWSMassillon95,63636321.2
Aqua Ohio - MarionMarion47,10277845.5
Wooster City PWSWooster26,61831518.4
Licking Regional Water DistrictBaltimore17,81835921
Jackson Co. Water Company - WTPJackson15,98429817.4
Rattlesnake PWSWashington Court House7,68546126.9
Warren Comm W and S Assn 2Marietta7,21532419
Gallipolis PWSGallipolis7,13425114.7
Covington Village PWSCovington2,71819011.1
Versailles Village PWSVersailles2,68751630.2
St Henry VillageSt Henry2,59683348.7
Columbus Grove VillageColumbus Grove2,13751229.9
Winesburg Area Development CorporationWinesburg1,57522012.9
Aqua Ohio - la Rue Village PWSMarion80051830.3
Oakwood Village PWSOakwood72737321.8
Malta Village PWSMalta67128216.5
Mount Eaton Village PWSWinesburg42530617.9
Hudson Estates PWSMorgantown41025214.7
Chickasaw VillageChickasaw35866638.9
Towbridge DevelopmentHudson35233819.8
Mantua Mobile Home ParkDurham25025314.8
Martinsburg Village PWSMartinsburg24024914.6
Aqua Ohio - Mansfield System #08Massillon17026415.4
Carvel Manor MHPDurham14847427.7
Granger Lake Condo 4 PWSMedina10824814.5
Deer Run McSalem10637722

Source: Ohio Environmental Protection Agency, Division of Drinking and Ground Waters, 48 utilities, results from Jan. 6, 2020 to Dec. 31, 2025, read Oct. 17, 2026. Each sampling point is taken at its median; a figure is typical where every point falls in one band.

Also: 4 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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