Ohio drinking water quality
Ohio has 4,165 active public water systems serving 11.2 million people. 2,054 of them, 49%, had at least one EPA violation in the past three years, 1,395 have an unresolved violation today, and 81 are designated serious violators by the EPA.
Active systems
4,165
in 88 counties
People served
11.2M
1,122 community systems serve 10.5M
Violations, past 3 years
2,054
49% of active systems
Serious violators
81
60 systems carry a health flag
Largest counties
All 88 countiesLargest community water systems
All 4,165 systems| System | Serves | Status |
|---|---|---|
| Columbus Public Water System Franklin County |
1,309,468 | |
| Cleveland Public Water System Cuyahoga County |
1,308,955 | |
| Cincinnati Public Water System Hamilton County |
800,000 | |
| Toledo City of Lucas County |
360,000 | |
| Akron City PWS Summit County |
280,000 | |
| Montgomery County Water Services 1 PWS Montgomery County |
150,207 | |
| Del-Co Water Company, Inc. Delaware County |
150,000 | |
| Dayton Public Water System Montgomery County |
141,407 | |
| Clermont Public Water System Clermont County |
133,059 | |
| Youngstown City PWS Mahoning County |
130,530 |
About the Ohio data
Retrieved from EPA ECHO on Oct 11, 2026. EPA records for Ohio systems do not include town names, so searches here match on ZIP code, street address, or county.