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, and 26,869 of them - about 6 in 10 - are still unresolved, with no recorded return-to-compliance date. The single most common violation is not lead and not PFAS: it is gross alpha particle activity, a measure of radioactivity that usually comes from naturally occurring uranium and radium in groundwater, cited at 6,717 systems. Chromium is a close second 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 contaminant, with the EPA's naming variants merged so no system is double-counted:
| Violation type | Systems cited | | --- | --- | | Gross alpha particle activity (radioactivity) | 6,717 | | Chromium | 6,269 | | Lead & Copper Rule | 3,793 | | Surface Water Treatment Rule | 3,192 | | Haloacetic acids (HAA5) | 3,169 | | Lead | 2,244 | | Arsenic | 2,005 | | Total trihalomethanes (TTHM) | 1,792 | | Total organic carbon | 1,745 | | Nitrite | 1,452 |
The top of this list surprises people, because it is not the contaminants that make headlines. Gross alpha and chromium together account for more cited systems than lead, PFAS, and arsenic combined. Two of the entries - haloacetic acids and trihalomethanes - are disinfection byproducts: they form when chlorine used to kill bacteria reacts with organic matter in the water, which is why total organic carbon (the raw material for that reaction) sits on the list too.
| 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.
Gross alpha particle activity is the most-cited violation, and it is the least understood. It measures alpha radiation in water, which almost always comes from naturally occurring radionuclides - uranium, radium, and their decay products - dissolved out of the rock that groundwater flows through. It is a geology problem more than a pollution problem, concentrated in regions with uranium-bearing aquifers, and the federal limit is 15 picocuries per liter. A violation means the water carried more radioactivity than that limit allows.
Chromium is the second most-cited. The federal standard is a total-chromium limit of 100 parts per billion. Chromium's most toxic form is hexavalent chromium, or chromium-6 - the industrial contaminant Erin Brockovich made famous - and it is worth being precise about the regulation: the EPA controls chromium-6 through that single total-chromium limit rather than a separate federal chromium-6 standard, so a "chromium" violation in this data is a total-chromium exceedance, which can include the hexavalent form.
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; the 26,869 unresolved ones are the more pressing group, because the record shows no return to compliance. 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. About 26,869 of those systems - roughly 6 in 10 - have no recorded return-to-compliance date, so their violation is still open.
Gross alpha particle activity - a measure of radioactivity, usually from naturally occurring uranium and radium in groundwater - is the most common, cited at 6,717 systems. Chromium is second at 6,269 systems. Neither is the contaminant most people expect; lead and PFAS rank below both.
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].