Best Water Quality Counties in Arizona
EPA drinking water health violations and safety grades Compare rankings across all 15 counties.
All Arizona Counties Ranked
| # | County | Water Quality Score | Overall Score |
|---|---|---|---|
| 1 | Maricopa County, AZ | 68 | 32.6 |
| 2 | Pima County, AZ | 53.4 | 26.9 |
| 3 | Graham County, AZ | 37 | 47.6 |
| 4 | Santa Cruz County, AZ | 34.5 | 39.9 |
| 5 | Apache County, AZ | 34.3 | 51.9 |
| 6 | Coconino County, AZ | 33.6 | 35.2 |
| 7 | Pinal County, AZ | 30.4 | 37.5 |
| 8 | Mohave County, AZ | 26.2 | 32.9 |
| 9 | Navajo County, AZ | 24.7 | 39.9 |
| 10 | Cochise County, AZ | 21.7 | 39.9 |
| 11 | Yavapai County, AZ | 18.6 | 40.7 |
| 12 | Gila County, AZ | 16.6 | 34.3 |
| 13 | Yuma County, AZ | 15.2 | 34.8 |
| 14 | La Paz County, AZ | 9.8 | 37.2 |
| 15 | Greenlee County, AZ | 5.2 | 70.1 |
Data Source
Water Quality data from WaterByCounty. See full details at WaterByCounty. Data updated February 2026.