Indiana drinking water quality
Indiana has 3,935 active public water systems serving 5.8 million people. 2,391 of them, 61%, had at least one EPA violation in the past three years, 455 have an unresolved violation today, and 82 are designated serious violators by the EPA.
Active systems
3,935
in 92 counties
People served
5.8M
767 community systems serve 5.2M
Violations, past 3 years
2,391
61% of active systems
Serious violators
82
144 systems carry a health flag
Largest counties
All 92 counties| County | People served | Systems | With violations |
|---|---|---|---|
| Marion | 948,624 | 56 | 37 |
| Lake | 535,388 | 111 | 73 |
| Allen | 323,472 | 86 | 42 |
| Hamilton | 229,378 | 66 | 34 |
| St. Joseph | 219,938 | 220 | 135 |
| Vanderburgh | 195,582 | 6 | 3 |
| Clark | 186,451 | 11 | 5 |
| Tippecanoe | 175,886 | 89 | 57 |
| Johnson | 154,825 | 33 | 20 |
| Elkhart | 138,805 | 284 | 162 |
Largest community water systems
All 3,935 systems| System | Serves | Status |
|---|---|---|
| Citizens Water Indianapolis Marion County |
880,345 | |
| Fort Wayne 3 Rivers Filtration Plant Allen County |
269,994 | |
| Indiana American Water Northwest Lake County |
210,510 | |
| Evansville Water Utility Vanderburgh County |
182,444 | |
| South Bend Water Works St. Joseph County |
115,000 | |
| Indiana American Water S. Indiana Clark County |
104,445 | |
| Carmel Water Department Hamilton County |
99,927 | |
| Indiana American Water Johnson County Johnson County |
86,813 | |
| City of Bloomington Utilities Monroe County |
83,000 | |
| Hammond Water Works Department Lake County |
78,384 |
About the Indiana data
Retrieved from EPA ECHO on Oct 11, 2026.