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EPA SDWIS ~155K water systems EPA + UCMR5

Arsenic

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: 1005

Total Violations
171,997
Systems Affected
16,264
Health-Based %
57.1%
Most Affected State
-

What this means

Arsenic appears in EPA SDWIS with 171,997 recorded violations across 16,264 public water systems. Of those, 57.1% 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

Arsenic violations broken down by EPA classification.

Health-based (57.1%) Monitoring/Reporting (42.9%)

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
Eakly Development Corp OK 1,062 277
City of Wolfforth TX 896 9,600
Tri County Sud TX 794 5,353
Bruni Rural WSC TX 689 350
Tempe WSC 1 TX 656 2,725
City of Seagraves TX 629 2,417
Duval County Crd Benavides TX 599 2,285
Gallery Acres West IA 584 43
Pb & SC Water Supply Corporation TX 573 2,163
Lynwood 3rd Addition IL 548 100
Stormlight Mobile Home Park TX 544 76
Eol WSC TX 533 2,195
City of Seminole TX 532 7,386
M S WSC TX 499 744
Ellinger Sewer and WSC TX 483 573
Leroy Tours Gerald WSC TX 480 1,680
Danvers IL 461 1,183
City of Smyer TX 450 474
Town North Village Water System TX 443 360
City of Plains TX 438 1,355
Hanford, City Of CA 413 62,127
Jim Hogg County Wcid 2 TX 410 5,397
Prairie Hill WSC TX 402 2,145
Axtell WSC TX 389 1,320
Welch WSC TX 378 315
City of Wellman TX 376 200
City of Riesel TX 365 1,476
Camino Real Regional Utility Authority NM 358 19,466
City of Andrews TX 358 14,109
Loma Escondida Water Association NM 351 89

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 Arsenic in drinking water? ▼
Arsenic is a contaminant tracked by the EPA under the Safe Drinking Water Act. It has caused 171,997 violations across 16,264 public water systems nationwide. 57.1% of these violations are health-based, meaning the contaminant exceeded Maximum Contaminant Levels (MCLs) or treatment technique requirements.
How many water systems have Arsenic violations? ▼
16,264 public water systems across the United States have at least one Arsenic violation recorded in the EPA SDWIS database.
Are Arsenic violations dangerous? ▼
57.1% of Arsenic 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 Arsenic 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.

Related

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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.