Water Quality · Arizona
Best Water Quality Counties in Arizona 2026
Ranked by EPA drinking water health violations.
Top 10 — Water Quality in Arizona
Score reflects water quality only — not overall county quality.
All Arizona Counties — Water Quality Rankings
15 counties ranked by water quality score. Overall Score shown for context.
| # | County | Water Quality Score | Overall Score |
|---|---|---|---|
| 1 | Maricopa County, AZ | 68 | 32.8 |
| 2 | Pima County, AZ | 53.4 | 27.5 |
| 3 | Graham County, AZ | 37 | 48.7 |
| 4 | Santa Cruz County, AZ | 34.5 | 39.4 |
| 5 | Apache County, AZ | 34.3 | 51 |
| 6 | Coconino County, AZ | 33.6 | 35.5 |
| 7 | Pinal County, AZ | 30.4 | 37.8 |
| 8 | Mohave County, AZ | 26.2 | 33.2 |
| 9 | Navajo County, AZ | 24.7 | 39.7 |
| 10 | Cochise County, AZ | 21.7 | 40.2 |
| 11 | Yavapai County, AZ | 18.6 | 40.9 |
| 12 | Gila County, AZ | 16.6 | 35.4 |
| 13 | Yuma County, AZ | 15.2 | 35.7 |
| 14 | La Paz County, AZ | 9.8 | 36.4 |
| 15 | Greenlee County, AZ | 5.2 | 69.1 |