The Most Common Water Violation in America Isn't Contamination. It's a Missing Report.

We've written about US water violations three ways now: ranked by state, ranked by rate, and ranked by how long they've sat unresolved. This time we ranked by type — what's actually broken, not where or for how long. One answer accounted for more than half the list.

3,335 of the 6,279 health-based violations open across US water systems right now — 53% — fall under a single EPA rule: the Lead and Copper Rule. That's more than double the next-largest category, the Groundwater Rule (1,902). And within that 3,335, one specific failure dominates almost completely.

It's not a lead reading. It's a missing form.

2,973 of those 3,335 Lead and Copper Rule violations — 89% — are systems that never submitted their Lead Service Line Inventory, the pipe-material survey every US community water system was required to file with the EPA by October 16, 2024. Not a lead level over the action limit. Not a failed corrosion-control study. A missing inventory. That's 2,968 separate water systems — 70% of every one of the 4,218 systems nationwide carrying any open health-based violation, of any kind — flagged for this one thing. Almost all of it is recent: 2,633 of the violations date to 2024 (the year the inventory was due) and another 329 to 2025.

We saw a piece of this before, in a narrower slice: 381 US school water systems carry an open health violation, and 301 of them are this exact same failure. It turns out that wasn't a school problem. It's the single most common reason any water system in America is currently out of compliance.

Where it concentrates

Rank	State / territory	Systems missing the inventory
1	California	774
2	Texas	418
3	Connecticut	323
4	Florida	319
5	Puerto Rico	236
6	Oklahoma	197
7	New Mexico	128
8	Illinois	81
9	Arizona	68
10	Michigan	44

Some are cities you'd recognize — West Sacramento, CA, Hallandale Beach, FL, Chickasha, OK. Most aren't municipal utilities at all. Connecticut's 323 are almost entirely small, separately regulated systems — the well that serves an apartment complex, a private school, a single factory — each legally required to file its own inventory whether it has five service connections or 50,000.

What "Lead and Copper Rule violation" actually means

This is worth being precise about, because "lead violation" reads as an alarm and the data doesn't support that reading here. Under the rule, exceeding the lead action level isn't itself logged as a violation — it triggers a set of required next steps: corrosion control study, treatment installation, lead service line replacement, public education, and the inventory. Failing any of those required steps is what generates a Treatment Technique violation. In the current national dataset, zero of the 3,335 open Lead and Copper Rule violations are a direct measured exceedance — every one is a procedural or treatment-technique failure, and 89% of those are specifically the inventory itself.

That doesn't make it a non-issue. The inventory exists so a system — and its customers — know where the lead pipes actually are. A system that hasn't filed one hasn't necessarily found lead, but it also can't tell you it hasn't, because it hasn't looked in the way the rule requires.

What "open" means here

Same definitions as every violations piece on this site. Health-based means the violation ties to a rule the EPA wrote to protect health, not a routine paperwork requirement outside that category. Open means the EPA's own status field still reads Unaddressed or Addressed — not Resolved, not Archived — in the latest SDWIS records. Violation types, rule families, and contaminant codes all come from EPA's own published code reference (SDWA_REF_CODE_VALUES), not an internal guess.

None of this covers microplastics. The Lead and Copper Rule, like every rule referenced above, regulates a contaminant the EPA already enforces. Microplastics aren't regulated at all — a system with a clean lead-service-line inventory and one that hasn't filed are equally not required to test for plastic in the water. The only way to get that answer for your own tap is to test it directly — a microplastics test kit does it at home in about 15 minutes.

Look up your own system

Every system named here — and every other US water system — is on the map, with its full EPA violation history. Start with California, Texas, or Connecticut, or search your own city.