Well water hardness in Colorado
Across 34 counties of Colorado, the median well sampled by the USGS has 9.2 gpg of hardness. Counties range from 3 gpg (Gilpin County) to 27.4 gpg (Pueblo 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 | ||
|---|---|---|---|---|
| Pueblo County | 27.4 | 469 | 47 | very hard |
| Denver County | 23.3 | 399 | 50 | very hard |
| Arapahoe County | 22.2 | 380 | 85 | very hard |
| Garfield County | 21.3 | 365 | 23 | very hard |
| Archuleta County | 20.2 | 345 | 21 | very hard |
| Moffat County | 19.9 | 341 | 27 | very hard |
| Mesa County | 18.4 | 316 | 10 | very hard |
| Fremont County | 17.6 | 301 | 34 | very hard |
| Montrose County | 16.9 | 290 | 19 | very hard |
| Adams County | 16.8 | 288 | 44 | very hard |
| Eagle County | 16.2 | 277 | 44 | very hard |
| Rio Blanco County | 15.4 | 263 | 64 | very hard |
| El Paso County | 13.7 | 234 | 298 | very hard |
| Boulder County | 13.6 | 233 | 35 | very hard |
| Routt County | 12.5 | 213 | 58 | very hard |
| Las Animas County | 12.3 | 210 | 43 | very hard |
| Yuma County | 9.2 | 158 | 21 | hard |
| Park County | 9.2 | 157 | 200 | hard |
| Alamosa County | 9.1 | 155 | 75 | hard |
| Gunnison County | 8.6 | 148 | 25 | hard |
| Douglas County | 7.9 | 135 | 42 | hard |
| Jefferson County | 7.6 | 130 | 134 | hard |
| Clear Creek County | 7.5 | 128 | 13 | hard |
| La Plata County | 7 | 120 | 61 | hard |
| Rio Grande County | 7 | 120 | 41 | hard |
| Lake County | 6.2 | 106 | 11 | moderately hard |
| Summit County | 6.1 | 105 | 20 | moderately hard |
| Saguache County | 5.5 | 94 | 50 | moderately hard |
| Elbert County | 4.6 | 79 | 29 | moderately hard |
| Chaffee County | 4.3 | 74 | 31 | moderately hard |
| Conejos County | 4.1 | 70 | 28 | moderately hard |
| Grand County | 3.8 | 64 | 36 | moderately hard |
| Delta County | 3.7 | 63 | 29 | moderately hard |
| Gilpin County | 3 | 52 | 14 | soft |
Counties with fewer than 10 sampled wells, or a median outside 5–500 mg/L, are not shown until the figure is reviewed.
Colorado: tap water hardness by city → · Well water hardness by state and county →