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Not health advice. Contact your local water utility for concerns.
Data from EPA Water Quality Reports. For official information, contact your water utility or health department.
Compare water quality across 17 counties in Colorado
17 counties ranked by average water quality score
| Rank | County | Avg Score | Grade | Cities | Population | Score Range |
|---|---|---|---|---|---|---|
| 1 | Routt County | 95 | A+ | 1 | 13,932 | 95 - 95 |
| 2 | Broomfield County | 93 | A | 1 | 74,112 | 93 - 93 |
| 3 | Mesa County | 90 | A | 1 | 65,560 | 90 - 90 |
| 4 | Eagle County | 87 | A- | 1 | 5,305 | 87 - 87 |
| 5 | Boulder County | 85 | A- | 3 | 236,520 | 65 - 96 |
| 6 | Montrose County | 82 | B+ | 1 | 20,291 | 82 - 82 |
| 7 | Morgan County | 81 | B+ | 1 | 11,555 | 81 - 81 |
| 8 | Adams County | 79 | B | 5 | 401,185 | 68 - 93 |
| 9 | Weld County | 78 | B | 4 | 195,884 | 45 - 93 |
| 10 | Arapahoe County | 77 | B | 4 | 576,248 | 70 - 88 |
| 11 | Larimer County | 77 | B | 2 | 252,139 | 68 - 86 |
| 12 | Pueblo County | 77 | B | 1 | 111,876 | 77 - 77 |
| 13 | El Paso County | 76 | B | 2 | 510,944 | 68 - 83 |
| 14 | Denver County | 74 | B- | 1 | 715,522 | 74 - 74 |
| 15 | Jefferson County | 60 | C | 4 | 333,773 | 49 - 84 |
| 16 | Douglas County | 59 | C- | 2 | 131,670 | 53 - 65 |
| 17 | La Plata County | 51 | D | 1 | 19,399 | 51 - 51 |
1 cities • 13,932 residents
1 cities • 74,112 residents
1 cities • 65,560 residents
1 cities • 5,305 residents
3 cities • 236,520 residents
1 cities • 20,291 residents
1 cities • 11,555 residents
5 cities • 401,185 residents
4 cities • 195,884 residents
4 cities • 576,248 residents
2 cities • 252,139 residents
1 cities • 111,876 residents
See all 17 counties in the ranking table above
Our county-level water quality analysis aggregates data from municipal water systems across Colorado. Each county's score represents the average water quality across all analyzed cities within that county, weighted by population served.
With 17 counties and 35 cities analyzed, this data helps residents understand regional water quality patterns in Colorado. County scores range from 45/100 to 96/100, reflecting the diversity of water sources and treatment infrastructure across the state.
Currently, 3 counties in Colorado have average scores below 70, indicating potential water quality concerns. Residents in these areas should review their city's specific report and consider water filtration options.