Chlorine in U.S. Drinking Water

Chlorine is regulated under the EPA Safe Drinking Water Act, which sets enforceable Maximum Contaminant Levels (MCLs) and associated treatment technique requirements for public water systems. The EPA Safe Drinking Water Information System (SDWIS) tracks every recorded violation nationwide and links it back to the specific public water system (PWSID), violation type, and begin date.

Across the United States, PlainEnviro's joined extract contains 353 health-based violation records carrying Chlorine (EPA code 0999) across 56 active community water systems in 10 states. Raw record counts are highest in Oklahoma, Louisiana, Missouri, with Oklahoma accounting for 33 records across 5 systems. Health-effect prose is shown only when the official ECHO substance name matches a verified topic; otherwise the portal stays silent rather than inventing guidance.

A health-based violation does not mean residents were necessarily harmed, it means the contaminant exceeded the federal MCL in a compliance sample, triggering notification and remediation requirements. States and utilities maintain primary enforcement responsibility. To check the status of a specific water system, request its most recent Consumer Confidence Report or consult the EPA's Drinking Water Watch portal for the corresponding state.