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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 16 counties in Iowa
16 counties ranked by average water quality score
| Rank | County | Avg Score | Grade | Cities | Population | Score Range |
|---|---|---|---|---|---|---|
| 1 | Pottawattamie County | 96 | A+ | 1 | 62,799 | 96 - 96 |
| 2 | Cerro Gordo County | 96 | A+ | 1 | 27,338 | 96 - 96 |
| 3 | Clinton County | 94 | A | 1 | 24,469 | 94 - 94 |
| 4 | Marshall County | 94 | A | 1 | 27,790 | 94 - 94 |
| 5 | Story County | 90 | A | 1 | 66,258 | 90 - 90 |
| 6 | Johnson County | 88 | A- | 3 | 118,616 | 81 - 94 |
| 7 | Wapello County | 88 | A- | 1 | 24,505 | 88 - 88 |
| 8 | Scott County | 83 | B+ | 2 | 140,826 | 79 - 87 |
| 9 | Polk County | 82 | B+ | 5 | 420,907 | 69 - 96 |
| 10 | Des Moines County | 82 | B+ | 1 | 24,858 | 82 - 82 |
| 11 | Muscatine County | 82 | B+ | 1 | 23,797 | 82 - 82 |
| 12 | Woodbury County | 81 | B+ | 1 | 85,797 | 81 - 81 |
| 13 | Black Hawk County | 76 | B | 2 | 108,880 | 73 - 78 |
| 14 | Linn County | 74 | B- | 2 | 179,245 | 64 - 84 |
| 15 | Dubuque County | 72 | B- | 1 | 59,667 | 72 - 72 |
| 16 | Webster County | 68 | C+ | 1 | 24,000 | 68 - 68 |
1 cities • 62,799 residents
1 cities • 27,338 residents
1 cities • 24,469 residents
1 cities • 27,790 residents
1 cities • 66,258 residents
3 cities • 118,616 residents
1 cities • 24,505 residents
2 cities • 140,826 residents
5 cities • 420,907 residents
1 cities • 24,858 residents
1 cities • 23,797 residents
1 cities • 85,797 residents
See all 16 counties in the ranking table above
Our county-level water quality analysis aggregates data from municipal water systems across Iowa. Each county's score represents the average water quality across all analyzed cities within that county, weighted by population served.
With 16 counties and 25 cities analyzed, this data helps residents understand regional water quality patterns in Iowa. County scores range from 64/100 to 96/100, reflecting the diversity of water sources and treatment infrastructure across the state.
Currently, 1 counties in Iowa 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.