US Water Quality Map
Interactive heatmap of drinking water quality across America. Click any state to see city-level data, then click a city for detailed contamination info. Data sourced from EPA SDWIS and UCMR5.
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States with Most Water Quality Issues
| State | Score | Cities | PFAS |
|---|---|---|---|
| 1. North Carolina | 26 | 10 | 0 |
| 2. Texas | 27 | 24 | 0 |
| 3. Florida | 27 | 23 | 0 |
| 4. South Carolina | 29 | 4 | 0 |
| 5. Alaska | 40 | 135 | 0 |
| 6. California | 44 | 28 | 0 |
| 7. Ohio | 45 | 8 | 0 |
| 8. Missouri | 47 | 13 | 0 |
| 9. Indiana | 49 | 16 | 0 |
| 10. South Dakota | 51 | 8 | 0 |
States with Best Water Quality
| State | Score | Cities | PFAS |
|---|---|---|---|
| 1. Wisconsin | 92 | 10 | 0 |
| 2. Nebraska | 91 | 1 | 0 |
| 3. Michigan | 81 | 26 | 0 |
| 4. Arkansas | 75 | 53 | 0 |
| 5. Kansas | 73 | 19 | 0 |
| 6. Montana | 72 | 6 | 0 |
| 7. Alabama | 70 | 327 | 0 |
| 8. West Virginia | 66 | 12 | 0 |
| 9. Kentucky | 66 | 5 | 0 |
| 10. Idaho | 66 | 4 | 0 |
Frequently Asked Questions
How is the water quality score calculated?
Each state and city receives a score from 0-100 based on three factors: contaminants detected above EPA limits, active drinking water violations, and the presence of PFAS (forever chemicals). A score of 90+ is Excellent, while below 30 is Critical.
Where does the water quality data come from?
All data comes directly from the EPA Safe Drinking Water Information System (SDWIS) and the Fifth Unregulated Contaminant Monitoring Rule (UCMR5). This includes violation records, contaminant testing results, and PFAS sampling data from community water systems across America.
How often is the map data updated?
The map data is refreshed regularly as new EPA data becomes available. UCMR5 sampling data is collected on a rolling basis from public water systems, and violation records are updated as states report to the EPA.
What are PFAS and why are they on the map?
PFAS (per- and polyfluoroalkyl substances) are synthetic chemicals known as "forever chemicals" because they persist in the environment indefinitely. In April 2024, the EPA established the first-ever enforceable limits for six PFAS compounds in drinking water. The map highlights which communities have detected PFAS.
Can I get notified when water quality changes in my area?
Yes! Sign up for free water quality alerts on this page. You can choose to receive email notifications, text alerts, or both whenever new data is published for your area.