Water Quality Analysis
Rankings, trends, and contaminant data across 17,254 American cities
Explore which states and cities have the most drinking water violations, and which contaminants most frequently exceed EPA safety limits.
17,254
Cities Tracked
47,125
Water Systems
1,810,888
Total Violations
199,671
Health Violations
319M
People Served
State Rankings
Most Total Violations
| # | State | Violations |
|---|---|---|
| 1 | Texas | 263,180 |
| 2 | Pennsylvania | 199,265 |
| 3 | Oklahoma | 128,472 |
| 4 | New York | 93,834 |
| 5 | West Virginia | 81,622 |
Most Health Violations
| # | State | Health Viol. |
|---|---|---|
| 1 | Texas | 39,140 |
| 2 | Oklahoma | 29,472 |
| 3 | California | 18,881 |
| 4 | Louisiana | 16,153 |
| 5 | New Mexico | 7,761 |
Most Violations Per Capita
| # | State | Per 100K |
|---|---|---|
| 1 | Alaska | 10,512.34 |
| 2 | West Virginia | 5,276.33 |
| 3 | Oklahoma | 3,516.1 |
| 4 | Vermont | 2,647.42 |
| 5 | Wyoming | 2,569.78 |
City Rankings
Most Common Contaminants
The contaminants most frequently found in violation of EPA standards across American water systems.
| # | Contaminant | Cities Affected |
|---|---|---|
| 1 | Stage 2 DBP | 2,686 |
| 2 | TTHM | 1,944 |
| 3 | Disinfection Byproducts | 1,930 |
| 4 | E. coli | 1,844 |
| 5 | Chlorine Dioxide | 1,635 |
| 6 | Gross Alpha | 1,290 |
| 7 | Total Haloacetic Acids (HAA5) | 1,265 |
| 8 | Chlorine | 892 |
| 9 | Fecal Coliform | 766 |
| 10 | Barium | 519 |
Data Sources
All data from the EPA Safe Drinking Water Information System (SDWIS) via the Envirofacts API. Community water systems serving 100+ people are included. Data is updated quarterly.