About WaterSafety

Why EPA SDWIS data deserves a public-facing home

The EPA Safe Drinking Water Information System (SDWIS) is the federal database of every public water system in the United States — every utility, every regulated chemical contaminant, every violation of the Safe Drinking Water Act. The system covers the entire country and is updated continuously as state agencies report violations to EPA. It is the only comprehensive public record of U.S. drinking-water safety. The official EPA presentation is built for state water-quality regulators; what is missing is a layer that lets a resident or homeowner look up the safety record of their own water system in seconds rather than after a multi-step navigation.

WaterSafety builds that layer. Every public water system has its own page showing the violation history, the population served, the source type (ground water, surface water), and the multi-year compliance record. Every city page consolidates the water systems serving the city; every state page rolls up to the state-level picture. The data is the EPA’s; the value the site adds is the address-to-water-system navigation.

How the SDWIS pipeline works

The pipeline pulls the EPA SDWIS Federal Reporting Services data quarterly. Each pull touches every active public water system and merges violation records, population served, and compliance status into the per-system pages. State and federal violations are categorized separately on the page so readers can distinguish health-based violations (exceedances of MCLs) from procedural violations (late reports, monitoring schedule misses).

A practical detail: not every household is on a public water system. Roughly 13 percent of U.S. households rely on private wells, which are not regulated by the Safe Drinking Water Act and not covered by SDWIS. The site focuses on public-system service; private-well households need separate testing through the local health department.

Where drinking-water data has caveats

Three things to know. First, EPA SDWIS captures regulated contaminants under the Safe Drinking Water Act. Emerging contaminants (PFAS in many states, microplastics, pharmaceuticals at trace levels) are not currently subject to federal MCLs and therefore do not produce violations even when present. The pages note known emerging-contaminant concerns where state-level data is available.

Second, the violation history reflects what the utility reported and what the state agency forwarded to EPA. Reporting completeness varies by state; states with stronger oversight produce more complete records, which can paradoxically make their utilities look worse on the federal record than utilities in states with thinner oversight.

Third, lead and copper contamination is regulated under a separate framework (the Lead and Copper Rule) and the action level is not an MCL. Lead-pipe service-line replacement is a multi-decade national project The methodology page on this site documents every dataset, every refresh cadence, and every limitation in detail so readers can trace any numeric value on the site back to the underlying federal source. We treat that traceability as a hard requirement for any data product that asks readers to make real-world decisions on its output.; the pages flag known lead-service-line issues at the system level.