Arsenic in U.S. Drinking Water
Health-based violation data for Arsenic from EPA Safe Drinking Water Information System (SDWIS). Covers all community water systems with violations on record.
Arsenic has been found in violation of EPA standards in 1,512 water systems across 43 states, with 30,331 total health-based violations recorded. The most affected states are Texas, California, Arizona.
Arsenic is regulated under the EPA Safe Drinking Water Act, which sets enforceable Maximum Contaminant Levels (MCLs) and associated treatment technique requirements for public water systems. The EPA Safe Drinking Water Information System (SDWIS) tracks every recorded violation nationwide and links it back to the specific public water system (PWSID), violation type, and begin date.
Across the United States, PlainEnviro's joined extract contains 30,331 health-based violation records carrying Arsenic (EPA code 1005) across 1,512 active community water systems in 43 states. Raw record counts are highest in Texas, California, Arizona, with Texas accounting for 6,232 records across 112 systems. EPA health-effect summaries describe the specific exposure concerns that drove the federal standard.
A health-based violation does not mean residents were necessarily harmed, it means the contaminant exceeded the federal MCL in a compliance sample, triggering notification and remediation requirements. States and utilities maintain primary enforcement responsibility. To check the status of a specific water system, request its most recent Consumer Confidence Report or consult the EPA's Drinking Water Watch portal for the corresponding state.
What are the health effects of this contaminant?
Arsenic is a naturally occurring contaminant that, with long-term exposure above EPA limits, is linked to skin damage, circulatory problems, and increased cancer risk.
Source: U.S. Environmental Protection Agency. Consult your doctor for personalized health guidance
Violations by State
States ranked by number of health-based violations for Arsenic.
| # | State | Violations | Systems Affected |
|---|---|---|---|
| 1 | Texas | 6,232 | 112 |
| 2 | California | 5,537 | 146 |
| 3 | Arizona | 2,139 | 83 |
| 4 | New Mexico | 1,064 | 26 |
| 5 | Oregon | 466 | 20 |
| 6 | Washington | 436 | 33 |
| 7 | Minnesota | 405 | 20 |
| 8 | Illinois | 370 | 30 |
| 9 | Nevada | 360 | 20 |
| 10 | Oklahoma | 359 | 13 |
| 11 | Missouri | 345 | 11 |
| 12 | New Hampshire | 294 | 52 |
| 13 | Alaska | 281 | 13 |
| 14 | New York | 269 | 14 |
| 15 | Nebraska | 265 | 15 |
| 16 | Louisiana | 213 | 10 |
| 17 | Colorado | 201 | 11 |
| 18 | Idaho | 186 | 17 |
| 19 | Iowa | 186 | 12 |
| 20 | Michigan | 137 | 19 |
| 21 | Indiana | 131 | 9 |
| 22 | Kansas | 131 | 8 |
| 23 | Pennsylvania | 127 | 15 |
| 24 | Montana | 118 | 10 |
| 25 | Maine | 106 | 11 |
| 26 | Utah | 98 | 5 |
| 27 | Mississippi | 69 | 3 |
| 28 | Ohio | 64 | 5 |
| 29 | Massachusetts | 54 | 5 |
| 30 | Georgia | 51 | 5 |
| 31 | Connecticut | 43 | 6 |
| 32 | North Carolina | 36 | 3 |
| 33 | Florida | 31 | 6 |
| 34 | New Jersey | 28 | 1 |
| 35 | South Dakota | 21 | 3 |
| 36 | Vermont | 21 | 5 |
| 37 | Wisconsin | 21 | 4 |
| 38 | Maryland | 20 | 3 |
| 39 | Wyoming | 17 | 1 |
| 40 | North Dakota | 13 | 3 |
| 41 | Tennessee | 10 | 2 |
| 42 | Arkansas | 5 | 2 |
| 43 | Virginia | 4 | 1 |
Most Affected Water Systems
Top 50 water systems by number of Arsenic health-based violations.
Frequently Asked Questions
Is Arsenic in my water?
Arsenic has been detected in violation of EPA health standards in 1,512 water systems across 43 states. To check your specific utility, look up your annual Consumer Confidence Report (CCR) - water systems are required to disclose all violations.
How many water systems have Arsenic violations?
EPA SDWIS records show 1,512 community water systems with health-based Arsenic violations, totaling 30,331 violations. These represent cases where the contaminant exceeded the EPA Maximum Contaminant Level (MCL).
Which states have the most Arsenic violations?
The states with the most Arsenic violations are: Texas (6,232 violations), California (5,537 violations), Arizona (2,139 violations), New Mexico (1,064 violations), Oregon (466 violations).
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About This Data
Violation data is from the EPA Safe Drinking Water Information System (SDWIS). Only health-based violations are shown, these include Maximum Contaminant Level (MCL) and Treatment Technique (TT) violations. Monitoring and reporting violations are excluded. Data may not reflect the most current enforcement actions.
Source: U.S. Environmental Protection Agency, SDWIS Federal Reporting Services
Read our methodology - how this data is sourced, computed, and verified.