The Hardest Water in the US: Cities and States, Ranked
Among the 2,944 US cities serving 50,000+ people with measured hardness values, Saticoy, CA has the hardest water at 505.0 mg/L (29.5 gpg) — very hard on the USGS scale — while Larchmont, NY has the softest at 6.2 mg/L. By population-weighted median, Utah is the hardest-water state in the country.
Data updated July 6, 2026. Source: utility-reported water quality data, verified as documented in our methodology. By TapWaterData Editorial.
The 25 US Cities With the Hardest Water
Measured values only (utility-reported, or computed from utility-reported calcium and magnesium), cities serving at least 50,000 people.
| # | City | State | Hardness (mg/L) | gpg | Category | Population served | Data |
|---|---|---|---|---|---|---|---|
| 1 | Saticoy | CA | 505.0 | 29.5 | Very hard | 113,500 | Utility-reported |
| 2 | San Buenaventura (Ventura) | CA | 476.8 | 27.9 | Very hard | 124,505 | Utility-reported |
| 3 | Lansing | MI | 446.0 | 26.1 | Very hard | 189,050 | Utility-reported |
| 4 | Herriman | UT | 424.0 | 24.8 | Very hard | 59,487 | Utility-reported |
| 5 | Twin Falls | ID | 400.0 | 23.4 | Very hard | 50,527 | Utility-reported |
| 6 | Martinsburg | WV | 387.0 | 22.6 | Very hard | 81,955 | Utility-reported |
| 7 | Odessa | TX | 380.8 | 22.3 | Very hard | 123,768 | Utility-reported |
| 8 | Midland | TX | 380.3 | 22.2 | Very hard | 143,323 | Utility-reported |
| 9 | Kearns | UT | 365.0 | 21.4 | Very hard | 55,119 | Utility-reported |
| 10 | Pocatello | ID | 351.0 | 20.5 | Very hard | 57,073 | Utility-reported |
| 11 | San Angelo | TX | 345.9 | 20.2 | Very hard | 110,771 | Utility-reported |
| 12 | Eloy | AZ | 343.0 | 20.1 | Very hard | 133,768 | Utility-reported |
| 13 | Madison | WI | 341.0 | 19.9 | Very hard | 277,395 | Utility-reported |
| 14 | Fort Carson | CO | 335.0 | 19.6 | Very hard | 70,414 | Utility-reported |
| 15 | Security-Widefield | CO | 335.0 | 19.6 | Very hard | 67,544 | Utility-reported |
| 16 | Rockford | IL | 329.1 | 19.3 | Very hard | 147,283 | Utility-reported |
| 17 | Casper | WY | 327.0 | 19.1 | Very hard | 64,980 | Utility-reported |
| 18 | Waukesha | WI | 325.7 | 19.1 | Very hard | 72,098 | Utility-reported |
| 19 | Cedarville | MI | 324.0 | 18.9 | Very hard | 73,441 | Utility-reported |
| 20 | Eastwood | MI | 319.0 | 18.6 | Very hard | 192,992 | Utility-reported |
| 21 | Westwood | MI | 319.0 | 18.6 | Very hard | 192,992 | Utility-reported |
| 22 | Kalamazoo | MI | 318.9 | 18.6 | Very hard | 193,260 | Utility-reported |
| 23 | Clio | MI | 312.0 | 18.3 | Very hard | 167,190 | Utility-reported |
| 24 | Kansas City | KS | 303.0 | 17.7 | Very hard | 152,960 | Utility-reported |
| 25 | Tinley Park | IL | 300.0 | 17.5 | Very hard | 56,703 | Utility-reported |
The 25 US Cities With the Softest Water
Same rules, other end of the scale — large US cities where tap water is softest.
| # | City | State | Hardness (mg/L) | gpg | Category | Population served | Data |
|---|---|---|---|---|---|---|---|
| 1 | Larchmont | NY | 6.2 | 0.4 | Soft | 66,114 | Utility-reported |
| 2 | Mamaroneck | NY | 6.2 | 0.4 | Soft | 59,629 | Utility-reported |
| 3 | New Rochelle | NY | 6.2 | 0.4 | Soft | 65,629 | Utility-reported |
| 4 | Fletcher | NC | 7.8 | 0.5 | Soft | 235,983 | Utility-reported |
| 5 | Mills River | NC | 7.8 | 0.5 | Soft | 235,793 | Utility-reported |
| 6 | South Portland | ME | 8.0 | 0.5 | Soft | 142,000 | Utility-reported |
| 7 | Fall River | MA | 8.3 | 0.5 | Soft | 94,150 | Utility-reported |
| 8 | Massapequa Park | NY | 8.3 | 0.5 | Soft | 87,700 | Utility-reported |
| 9 | Berea | SC | 8.4 | 0.5 | Soft | 394,840 | Utility-reported |
| 10 | City View | SC | 8.4 | 0.5 | Soft | 394,840 | Utility-reported |
| 11 | Conestee | SC | 8.4 | 0.5 | Soft | 394,840 | Utility-reported |
| 12 | Dunean | SC | 8.4 | 0.5 | Soft | 394,840 | Utility-reported |
| 13 | Five Forks | SC | 8.4 | 0.5 | Soft | 394,840 | Utility-reported |
| 14 | Fountain Inn | SC | 8.4 | 0.5 | Soft | 394,840 | Utility-reported |
| 15 | Gantt | SC | 8.4 | 0.5 | Soft | 394,840 | Utility-reported |
| 16 | Golden Grove | SC | 8.4 | 0.5 | Soft | 394,840 | Utility-reported |
| 17 | Greenville | SC | 8.4 | 0.5 | Soft | 398,407 | Utility-reported |
| 18 | Judson | SC | 8.4 | 0.5 | Soft | 394,840 | Utility-reported |
| 19 | Mauldin | SC | 8.4 | 0.5 | Soft | 394,840 | Utility-reported |
| 20 | Parker | SC | 8.4 | 0.5 | Soft | 394,840 | Utility-reported |
| 21 | Pelzer | SC | 8.4 | 0.5 | Soft | 396,265 | Utility-reported |
| 22 | Piedmont | SC | 8.4 | 0.5 | Soft | 394,840 | Utility-reported |
| 23 | Sans Souci | SC | 8.4 | 0.5 | Soft | 394,840 | Utility-reported |
| 24 | Simpsonville | SC | 8.4 | 0.5 | Soft | 394,840 | Utility-reported |
| 25 | Slater-Marietta | SC | 8.4 | 0.5 | Soft | 398,095 | Utility-reported |
How This Ranking Works
- Measured tiers only: every ranked value is utility-reported hardness or hardness computed from utility-reported calcium and magnesium. Labeled county-level estimates never enter a city ranking.
- Disputed values excluded: cities whose reported tap values conflict beyond tolerance are flagged disputed and left out of the rankings entirely.
- Population floor of 50,000: rankings compare cities where the recorded utility serves at least 50,000 people, per our index. Where a known city-to-utility mis-mapping would otherwise drop a major city — Chicago and Las Vegas among them — we publish a cited, hand-verified correction so the city is represented by its real supply rather than excluded or guessed.
Full sourcing, tier definitions, tolerances, and verification rules: data & methodology.
States With the Hardest Water
Each state's number is the population-weighted median across every covered city in the state — including labeled county-level estimates (T3) — so states are compared on their full coverage, not just the cities with utility-reported values. "County estimates" counts how many of the state's cities carry an estimate rather than a measured value.
States With the Softest Water
| # | State | Median (mg/L) | Median (gpg) | Cities in median | County estimates |
|---|---|---|---|---|---|
| 1 | Maine | 14.2 | 0.8 | 124 | 36 |
| 2 | South Carolina | 15.0 | 0.9 | 230 | 152 |
| 3 | Oregon | 22.6 | 1.3 | 225 | 176 |
| 4 | Georgia | 27.4 | 1.6 | 382 | 277 |
| 5 | North Carolina | 29.7 | 1.7 | 544 | 349 |
| 6 | Mississippi | 29.8 | 1.7 | 268 | 262 |
| 7 | New York | 30.8 | 1.8 | 683 | 441 |
| 8 | New Hampshire | 31.0 | 1.8 | 90 | 83 |
| 9 | Washington | 32.2 | 1.9 | 386 | 159 |
| 10 | Arkansas | 37.9 | 2.2 | 388 | 186 |
Want the regional picture city by city? See the interactive hardness map or start from the water hardness hub.
Cite this data
These rankings — and the full city-level dataset behind them — are free to republish under Creative Commons Attribution 4.0 (CC BY 4.0): credit TapWaterData with a link. Suggested citation:
TapWaterData Water Hardness Dataset, 2026. https://www.tapwaterdata.com/water-hardness — CC BY 4.0
Download the full dataset (CSV and JSON): open dataset. How every value is sourced and verified: methodology.
Water hardness tools
By TapWaterData Editorial.
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