Well water hardness in Arizona
Across 15 counties of Arizona, the median well sampled by the USGS has 11.2 gpg of hardness. Counties range from 7.6 gpg (Pima County) to 18.9 gpg (Yuma County).
Millions of American households drink water from their own well. No utility tests that water and no water quality report covers it. These pages summarise the hardness the U.S. Geological Survey measured in wells county by county, so you know what to expect before you test your own well.
Counties, hardest first
| gpg | mg/L | wells | ||
|---|---|---|---|---|
| Yuma County | 18.9 | 323 | 95 | very hard |
| Gila County | 15.8 | 270 | 93 | very hard |
| Yavapai County | 14.1 | 242 | 290 | very hard |
| Coconino County | 13.7 | 235 | 144 | very hard |
| Santa Cruz County | 12.3 | 210 | 29 | very hard |
| Apache County | 12 | 206 | 98 | very hard |
| Maricopa County | 11.4 | 195 | 558 | very hard |
| Pinal County | 11.2 | 193 | 230 | very hard |
| Mohave County | 11.1 | 191 | 217 | very hard |
| Cochise County | 8.8 | 151 | 351 | hard |
| Greenlee County | 8.6 | 148 | 17 | hard |
| Navajo County | 8.4 | 144 | 151 | hard |
| Graham County | 8.4 | 143 | 97 | hard |
| La Paz County | 8.2 | 140 | 162 | hard |
| Pima County | 7.6 | 131 | 184 | hard |
Counties with fewer than 10 sampled wells, or a median outside 5–500 mg/L, are not shown until the figure is reviewed.
Arizona: tap water hardness by city → · Well water hardness by state and county →