Clean drinking water is something most Americans take for granted until it isn’t clean. EPA’s Safe Drinking Water Information System (SDWIS) tracks violations at every public water system in the country, and the data reveals significant variation by state.
What EPA Tracks
SDWIS monitors two types of violations:
Health-based violations: Exceeding maximum contaminant levels (MCLs) for substances like lead, arsenic, nitrates, disinfection byproducts, and bacteria. These directly affect safety.
Monitoring and reporting violations: Failure to test or report results on schedule. These don’t necessarily mean the water is unsafe, but they mean nobody verified that it is.
HomeStats displays both violation counts on every state page.
States With the Most Violations
Violation counts correlate with the number of water systems in a state (Texas and California have thousands of small systems) and with infrastructure age. States with older pipe networks and underfunded utilities tend to have more health-based violations.
The specific numbers change quarterly as violations are issued and resolved. Check the HomeStats state pages for current data pulled from EPA SDWIS.
What This Means for Homeowners
Well Water vs. Municipal
If your home uses a private well, EPA regulations don’t apply. You’re responsible for testing and treatment. Well water testing costs $100-$500 depending on the panel and should be done annually.
Lead Pipes
The EPA’s Lead and Copper Rule Revisions require utilities to replace lead service lines, but the timeline stretches to 2037. If your home was built before 1986, there’s a chance the service line connecting your home to the water main is lead. Your utility should be able to tell you.
Water Treatment Options
For homes with concerning water quality:
| System | Cost | What It Removes |
|---|---|---|
| Pitcher filter | $30-$50 + $40/yr filters | Chlorine, some lead, taste |
| Faucet-mount | $20-$50 + $30/yr filters | Chlorine, lead, basic contaminants |
| Under-sink RO | $200-$500 + $100/yr filters | Most contaminants including lead, PFAS |
| Whole-house filter | $1,000-$3,000 + $200/yr | Sediment, chlorine, some chemicals |
| Whole-house RO | $3,000-$8,000 + $300/yr | Nearly everything |
PFAS (“Forever Chemicals”)
Per- and polyfluoroalkyl substances are a growing concern. EPA set maximum contaminant levels for several PFAS compounds in 2024. Many water systems are still testing and installing treatment. Under-sink reverse osmosis removes over 90% of PFAS compounds.
The EWG Alternative
The Environmental Working Group’s Tap Water Database applies stricter health-based guidelines than EPA’s legal limits. Many contaminants are detected at levels that are legal under EPA rules but above what EWG considers safe based on current health research.
If you want the most conservative assessment of your local water quality, check the EWG Tap Water Database by ZIP code.
Water Quality and Home Values
Documented water contamination events (like Flint, Michigan) can reduce home values 10-20% in affected areas. Even advisory notices can impact values. This is a factor worth researching before buying.
Water violation data for every state is available on the HomeStats state pages alongside flood risk, disaster history, and environmental data.
For the complete guide to environmental and cost factors in homeownership, read The Resale Trap.