How hard is the water in your city? These guides show the tap water hardness for major U.S. cities, based on utility-reported data, along with where the water comes from, nearby cities and the right water softener settings.
Hardness is measured in milligrams per liter (mg/L) or grains per gallon (GPG). Water above 7 GPG (120 mg/L) is hard, and above 10.5 GPG (180 mg/L) is very hard.
City Water Hardness Guides
| City | Hardness (mg/L) | GPG | Category | National rank |
|---|---|---|---|---|
| Madison, WI | 341 | 19.9 | Very hard | #1 |
| Henderson, NV | 282 | 16.5 | Very hard | #2 |
| Las Vegas, NV | 280 | 16.4 | Very hard | #3 |
| Phoenix, AZ | 237 | 13.9 | Very hard | #5 |
| San Diego, CA | 225 | 13.2 | Very hard | #7 |
| Jacksonville, FL | 189 | 11.1 | Very hard | #12 |
| Tucson, AZ | 180 | 10.5 | Hard | #14 |
| San Antonio, TX | 179 | 10.5 | Hard | #15 |
| Indianapolis, IN | 178 | 10.4 | Hard | #16 |
| Mesa, AZ | 141 | 8.2 | Hard | #27 |
National rank is out of 86 large U.S. cities in our study of cities with the hardest water in the USA. More city guides are being added.
Look Up Any ZIP Code
Not on the list? Check the hardness for your ZIP code or city:
Data: TapWaterData US Water Hardness Dataset (CC BY 4.0), based on utility water quality reports. ZIP locations: GeoNames (CC BY 4.0).
You can also compare all 50 states on our US hard water map.
Source: utility-reported data via the TapWaterData US Water Hardness Dataset (CC BY 4.0).