Ohio Water Systems

Ohio operates 1,094 community water systems regulated by the EPA Safe Drinking Water Information System (SDWIS) under the Safe Drinking Water Act. Together these utilities serve an estimated 10,443,946 residents, each filing compliance results with the state's primacy agency and, for federally listed contaminants, with the U.S. Environmental Protection Agency.

Across the state, SDWIS records contain 1,386 total violations, of which 310 systems carry at least one active health-based violation, a Maximum Contaminant Level (MCL) exceedance or treatment-technique failure. That represents roughly 28% of Ohio systems.

Violation counts reflect both infrastructure realities and reporting diligence, a state with more small rural systems will accumulate more monitoring-type violations without necessarily delivering worse water. Health-based violations are the stronger safety signal. A past violation does not itself indicate current unsafe water; utilities must notify customers, remediate, and publish an annual Consumer Confidence Report. All numbers below draw directly from the federal SDWIS record.