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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 13 counties in Idaho
13 counties ranked by average water quality score
| Rank | County | Avg Score | Grade | Cities | Population | Score Range |
|---|---|---|---|---|---|---|
| 1 | Nez Perce County | 100 | A | 1 | 20,000 | 100 - 100 |
| 2 | Banneville County | 99 | A | 1 | 15,842 | 99 - 99 |
| 3 | Jerome County | 99 | A | 1 | 13,135 | 99 - 99 |
| 4 | Latah County | 98 | A | 1 | 26,000 | 98 - 98 |
| 5 | Bonneville County | 97 | A | 2 | 86,788 | 93 - 100 |
| 6 | Canyon County | 95 | A | 2 | 174,200 | 89 - 100 |
| 7 | Kootenai County | 94 | A | 2 | 74,400 | 88 - 100 |
| 8 | Madison County | 90 | A | 1 | 40,695 | 90 - 90 |
| 9 | Ada County | 86 | B | 5 | 462,964 | 75 - 100 |
| 10 | Twin Falls County | 84 | B | 1 | 56,121 | 84 - 84 |
| 11 | Bannock County | 82 | B | 1 | 58,231 | 82 - 82 |
| 12 | Elmore County | 70 | C | 1 | 14,651 | 70 - 70 |
| 13 | Bingham County | 70 | C | 1 | 13,224 | 70 - 70 |
Our county-level water quality analysis aggregates data from municipal water systems across Idaho. Each county's score represents the average water quality across all analyzed cities within that county, weighted by population served.
With 13 counties and 20 cities analyzed, this data helps residents understand regional water quality patterns in Idaho. County scores range from 70/100 to 100/100, reflecting the diversity of water sources and treatment infrastructure across the state.
All analyzed counties in Idaho 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.