Washington utilities with hard water.
121 to 180 mg/L (7.1 to 10.5 grains per gallon). 195 utilities serving 139,488 people as they report it, largest first.
1 to 100 of 195, by people served
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.
Where to go next
- Washington hardnessEvery band in the state, with the largest utilities in each.Washington water hardness
- Softeners comparedCertified softeners and what each costs over five years, salt included, at your water’s hardness.Softeners, salt included
- Hardness across the USEvery state with hardness results, and the hardest and softest large utilities.US water hardness