Safe Drinking Water Act (SDWA)
The primary federal law governing drinking water quality — authorizing the EPA to set standards for contaminants in public water systems and requiring states to enforce those standards.
How It Works
The SDWA was passed in 1974 and significantly amended in 1986 and 1996. It authorizes the EPA to: set national primary drinking water standards (MCLs), require water systems to monitor for contaminants and report results, establish treatment requirements, protect underground sources of drinking water, and fund water system improvements through the Drinking Water State Revolving Fund. States have primary enforcement responsibility ("primacy") under the SDWA — they conduct inspections, review monitoring data, and take enforcement action. The EPA can step in if a state fails to act. The SDWA does not regulate private wells, which serve about 15% of the U.S. population — private well owners are responsible for their own water quality testing.
Related Terms
- Environmental Protection Agency (EPA) — The federal agency that sets drinking water standards, regulates public water systems, and publishes the data that IsWaterSafe uses to assess water safety.
- Maximum Contaminant Level (MCL) — The highest level of a contaminant allowed in drinking water — set by the EPA and enforceable by law. Exceeding the MCL triggers a health-based violation.
- SDWIS (Safe Drinking Water Information System) — The EPA database that tracks every public water system in the United States — violations, enforcement actions, contaminant levels, and system characteristics.
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About This Definition
This definition is part of the IsWaterSafe Drinking Water Safety Glossary — 22 terms explaining water contaminants, treatment methods, and safety standards. Written for homeowners, renters, journalists, and public health professionals.