Kentucky water hardness, by utility.
The short answer
Hard water reaches the most people here: 2 utilities serving 1.5 million.
The largest, Louisville Water Company, is hard, typically 130 mg/L (7.6 grains per gallon).
Hard
121 to 180 mg/L (7.1 to 10.5 grains per gallon). 2 utilities serving 1.5 million people, largest first.
| Utility | Based in | Serves | Hardness, mg/L | Grains per gallon |
|---|---|---|---|---|
| Louisville Water Company | Louisville | 806,997 | 130 | 7.6 |
| Kentucky - American Water Co | Lexington | 669,042 | 136 | 8 |
Moderately hard
61 to 120 mg/L (3.6 to 7 grains per gallon). 1 utility serving 53,601 people, largest first.
| Utility | Based in | Serves | Hardness, mg/L | Grains per gallon |
|---|---|---|---|---|
| Bowling Green Municipal Utilities | Bowling Green | 53,601 | 118 | 6.9 |
Source: Kentucky Division of Water, 3 utilities, results from April 1, 2015 to April 6, 2026, read Oct. 17, 2026. Each sampling point is taken at its median; a figure is typical where every point falls in one band.
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
- Softeners comparedCertified softeners and what each costs over five years, salt included, at your water’s hardness.Softeners, salt included
- Softener or conditioner?What each does about scale, what it costs to run, and the certification to look for.Softener or salt-free conditioner
- Hardness across the USEvery state with hardness results, and the hardest and softest large utilities.US water hardness
- Kentucky utilitiesEvery utility with a full report: what its results show, and its violations.Kentucky tap water