EPA SDWIS ~155K water systems EPA + UCMR5

Coliform (TCR)

Compiled by PlainWater Editorial, Drinking Water Quality Editorial Team · May 15, 2026

EPA SDWIS quarterly extract data for this analyte. Detection counts and health-based violation counts reflect the most recent federal release.

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EPA contaminant code: 3100

Total Violations

1,839,196

Systems Affected

98,293

Health-Based %

30.1%

Most Affected State

What this means

Coliform (TCR) appears in EPA SDWIS with 1,839,196 recorded violations across 98,293 public water systems. Of those, 30.1% are classified as health-based, meaning the reading exceeded a federally enforceable Maximum Contaminant Level or a treatment-technique requirement rather than a monitoring or reporting lapse. Health-based violations are the subset that trigger formal corrective action and public notification, so the share is a useful signal of real-world exposure risk rather than paperwork drift. State-level concentration data is not consistently reported for this contaminant, so regional interpretation should lean on the system table below rather than state aggregates. Utilities listed below are ranked by cumulative violation count, so a higher rank reflects persistence in the record rather than a single spike; readers comparing systems should consider population served alongside violation count to gauge how many households were actually exposed.

Violation Type Split

Coliform (TCR) violations broken down by EPA classification.

Health-based (30.1%) Monitoring/Reporting (69.9%)

Health-based violations indicate the contaminant exceeded an EPA Maximum Contaminant Level (MCL) or treatment-technique requirement; monitoring/reporting violations are procedural.

Most Affected Water Systems

System	State	Violations	Population
Rivershore Community LLC	MT	998	90
The Missing Well	MO	991	173
Hidden Valley MHP LLC	MO	943	60
Waterhole Saloon Reedpoint	MT	922	25
Coal Mountain Water	WV	901	80
Veguita	PR	831	90
Clear Creek RV Park	MO	780	100
Cubuy-Marines	PR	766	150
Villa Blanca	PR	764	306
Sist. Rural Graulao	PR	716	64
Acued. la Grama	PR	701	60
Sector Laguna	PR	679	27
Mogote	PR	676	140
Hacienda Rullan	PR	673	340
Sierrita	PR	662	268
Lucas Lugo	PR	661	40
Town of Charmwood	MO	655	28
Com. Saltos Cabra	PR	650	500
Palomas II	PR	648	47
Hacienda Planell	PR	637	25
Asoc. Pro Bienestar Magueyes	PR	636	140
Lumberton Mdwca	NM	634	223
Servicio de Agua	PR	633	300
Starlight Village	MO	631	65
La Cascada Milagrosa	PR	627	240
Hiawatha Water	WV	613	63
Pandura	PR	604	240
Alturas de Collores	PR	603	300
Key Road Subdivision Water System	TX	602	54
Veguitas Gripinas	PR	599	130

Drinking Water Guides

Understanding Water Quality Data

What EPA SDWIS tracks, how violations are classified, and what MCLs mean.

PFAS in Drinking Water

What forever chemicals are, EPA testing results, and 2024 standards.

Is My Water Safe?

How to assess your local water quality and when to take precautions.

Frequently Asked Questions

What is Coliform (TCR) in drinking water? ▼

Coliform (TCR) is a contaminant tracked by the EPA under the Safe Drinking Water Act. It has caused 1,839,196 violations across 98,293 public water systems nationwide. 30.1% of these violations are health-based, meaning the contaminant exceeded Maximum Contaminant Levels (MCLs) or treatment technique requirements.

How many water systems have Coliform (TCR) violations? ▼

98,293 public water systems across the United States have at least one Coliform (TCR) violation recorded in the EPA SDWIS database.

Are Coliform (TCR) violations dangerous? ▼

30.1% of Coliform (TCR) violations are health-based, meaning the contaminant level exceeded safe limits set by the EPA. Health-based violations require corrective action by the water system. Not all violations indicate immediate health risk, but they signal that water quality standards were not met.

Which state has the most Coliform (TCR) violations? ▼

State-level breakdown data is not available for this contaminant.

Where does this contaminant data come from? ▼

All violation data comes from the EPA Safe Drinking Water Information System (SDWIS), which tracks compliance for all public water systems regulated under the Safe Drinking Water Act. SDWIS records violations including Maximum Contaminant Level (MCL) exceedances, treatment technique failures, and monitoring/reporting issues.

Data Sources

Contaminant violation data from the EPA Safe Drinking Water Information System (SDWIS). Violations are categorized as health-based (Maximum Contaminant Level exceedances, treatment technique failures) or monitoring/reporting violations.

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Data sourced from EPA SDWIS and UCMR5 PFAS monitoring data. See our methodology for details. Retrieved and formatted by PlainWater Editorial

Disclaimer: This information is provided for informational purposes only and does not constitute professional advice. Data is sourced from the EPA Safe Drinking Water Information System (SDWIS). Consult a qualified professional before making decisions based on this data.

Read our methodology - how this data is sourced, computed, and verified.

Every figure on PlainWater is rendered directly from EPA SDWIS drinking-water data, no number is typed in by an editor. This page draws directly on EPA SDWIS data, no figure is typed in by an editor. See our editorial standards & corrections policy, the methodology behind these numbers, or report a data error.