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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 | Pueblo County | 100 | A | 1 | 114,070 | 100 - 100 |
| 2 | Eagle County | 100 | A | 1 | 51,515 | 100 - 100 |
| 3 | Montrose County | 100 | A | 1 | 19,305 | 100 - 100 |
| 4 | Routt County | 100 | A | 1 | 9,950 | 100 - 100 |
| 5 | Weld County | 98 | A | 4 | 222,623 | 97 - 100 |
| 6 | Jefferson County | 98 | A | 4 | 311,298 | 94 - 100 |
| 7 | La Plata County | 98 | A | 1 | 33,787 | 98 - 98 |
| 8 | Morgan County | 98 | A | 1 | 12,000 | 98 - 98 |
| 9 | Boulder County | 97 | A | 3 | 298,958 | 95 - 98 |
| 10 | Larimer County | 97 | A | 2 | 270,978 | 94 - 99 |
| 11 | Mesa County | 97 | A | 1 | 26,000 | 97 - 97 |
| 12 | El Paso County | 94 | A | 2 | 489,241 | 91 - 97 |
| 13 | Arapahoe County | 93 | A | 4 | 694,387 | 77 - 100 |
| 14 | Denver County | 90 | A | 1 | 1,287,000 | 90 - 90 |
| 15 | Broomfield County | 89 | B | 1 | 106,153 | 89 - 89 |
| 16 | Adams County | 84 | B | 5 | 609,333 | 64 - 100 |
| 17 | Douglas County | 84 | B | 2 | 186,247 | 79 - 88 |
4 cities • 311,298 residents
2 cities • 489,241 residents
4 cities • 694,387 residents
1 cities • 1,287,000 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 64/100 to 100/100, reflecting the diversity of water sources and treatment infrastructure across the state.
All analyzed counties in Colorado maintain average scores above 70, indicating generally acceptable water quality standards statewide. Individual city scores may vary, so residents should still review their specific city's report.