Most drinking-water coverage looks at one contaminant at a time - lead this month, PFAS the next. The EPA's enforcement records let you step back and ask the broader question instead: across every public water system in the country, how many are actually out of compliance, what for, and where? We pulled the full Safe Drinking Water Act violation record to answer it honestly.
The violations that matter here are the "health-based" ones. A health-based violation means a system either let a regulated contaminant rise above its federal limit, or skipped the treatment the law requires to keep that contaminant in check. It is not a late-paperwork or missed-monitoring slip - it is the enforceable, your-water-was-actually-affected kind. Here is what 174,123 of those violation records, across 44,435 water systems, show.
Across the EPA's Safe Drinking Water Act enforcement data, 44,435 US public water systems carry at least one health-based violation on record. The single most common problem is not PFAS or an industrial chemical: it is bacteria. Violations of the federal coliform rules, which track total coliform and E. coli as signs that disease-causing microbes could be getting into the water, are on record at 20,943 systems, nearly half of the total. The Lead and Copper Rule is a distant second at 11,696 systems, followed by the Ground Water Rule at 6,269. Pennsylvania, Texas, and California have the most systems with violations. Because one system can be cited for several contaminants at once, the per-contaminant counts add up to more than the 44,435 total.
The EPA sorts Safe Drinking Water Act violations into a few buckets, and the distinction matters before any number does.
The first two are the "health-based" violations in this analysis. They are the ones that reflect what was in the water, not just whether the paperwork was in order.
Counting the distinct public water systems cited for each violation type, grouped by the EPA's own contaminant and rule codes so no system is double-counted within a type:
| Violation type | Systems cited | | --- | --- | | Coliform bacteria (Total Coliform Rule and Revised Total Coliform Rule) | 20,943 | | Lead and Copper Rule (treatment technique) | 11,696 | | Ground Water Rule (treatment technique) | 6,269 | | Total trihalomethanes (TTHM) | 3,169 | | Surface water treatment rules (filtration and disinfection) | 2,868 | | Nitrate and nitrite | 2,621 | | Disinfection byproduct rule treatment technique (incl. total organic carbon removal) | 1,963 | | Haloacetic acids (HAA5) | 1,792 | | Arsenic | 1,452 | | Radionuclides (gross alpha, radium, uranium) | 888 |
The top of this list surprises people, because it is not the contaminants that make headlines. Microbial rules (coliform, ground water, and surface water treatment) dominate, and PFAS does not appear at all, because the 2024 federal PFAS limits are not enforceable until 2029. Three of the entries - trihalomethanes, haloacetic acids, and the disinfection byproduct treatment technique - belong to the disinfection byproduct rules: the byproducts form when chlorine used to kill bacteria reacts with organic matter in the water, which is why removing total organic carbon (the raw material for that reaction) is itself a requirement.
| State | Systems with a health-based violation | | --- | --- | | Pennsylvania | 4,035 | | Texas | 2,912 | | California | 2,854 | | New York | 1,961 | | Indiana | 1,694 | | Illinois | 1,491 | | Michigan | 1,433 | | North Carolina | 1,413 | | Wisconsin | 1,319 | | New Jersey | 1,252 |
These are counts of systems, not people, and they track partly with how many separate water systems a state has: Pennsylvania and Texas both run enormous numbers of small, rural systems, and small systems - with the least budget for treatment and the fewest staff - are where compliance is hardest. A big state with a few large, well-run utilities can serve more people with fewer violations than a state fragmented into hundreds of tiny ones.
Coliform bacteria violations are the most common by a wide margin. Coliforms are mostly harmless themselves, but they are the EPA's indicator that disease-causing microbes could be getting into the water through a treatment failure or a break in the distribution system. Under the original Total Coliform Rule, a system violated its limit when too many monthly samples tested positive. The Revised Total Coliform Rule, in effect since April 2016, set the legal limit on E. coli instead and requires systems to investigate and fix the cause when total coliform keeps showing up; skipping that assessment or correction is a treatment-technique violation.
The Lead and Copper Rule is second. Lead has no ordinary maximum contaminant level; the rule instead requires systems to sample high-risk homes and, when the 90th-percentile result is over the 15 ppb action level, to run corrosion control, public education, and lead service line replacement. A violation here means a required step was missed or not done on time, which is why it counts as health-based even when no single sample is cited. For the readings themselves, see The State of Lead in US Drinking Water.
A health-based violation on your system's record is a real signal, but read it carefully. It means the system was, at some point, out of compliance for that contaminant - not that today's glass of water is dangerous. Many violations are resolved with treatment upgrades, and a violation from the 1990s says much less about your water today than one from last year. The honest move is to look up your own system, see which contaminant was cited and whether it is still open, and decide from there.
Type your ZIP code into the free lookup and you will see the contaminants detected and any violations on record for the systems that serve your area - lead, chromium, radioactivity, disinfection byproducts, and the rest - drawn from this same EPA data.
44,435 US public water systems have at least one health-based Safe Drinking Water Act violation on record, drawn from 174,123 violation entries across all 50 states and DC. The record spans decades, so many of those violations have long since been resolved.
Coliform bacteria violations, under the Total Coliform Rule and the Revised Total Coliform Rule, are the most common, on record at 20,943 systems. The Lead and Copper Rule is second at 11,696 systems, and the Ground Water Rule third at 6,269. PFAS does not appear yet, because the 2024 federal PFAS limits are not enforceable until 2029.
Not necessarily. A health-based violation means a system exceeded a federal limit or skipped required treatment at some point, not that the current water is harmful. Whether the violation is still open matters most. Look up your ZIP code to see which contaminant was cited for your system and whether it has been resolved.
A health-based violation means a contaminant exceeded its federal limit or a required treatment was not applied - it reflects the water itself. A monitoring or reporting violation means the system did not test or did not file on time. This analysis counts only the health-based kind.
Cite this analysis (APA):
> Know Your Exposure Research Team. (2026). The State of Water Violations in US Drinking Water (2026). KnowYourExposure. https://knowyourexposure.com/blog/state-of-water-violations-in-us-drinking-water-2026
Journalists and researchers are welcome to cite these figures with a link back. For a custom data pull or a quote, contact [email protected].