Selenium in U.S. Drinking Water
Health-based violation data for Selenium from EPA Safe Drinking Water Information System (SDWIS). Covers all community water systems with violations on record.
Selenium has been found in violation of EPA standards in 197 water systems across 5 states, with 1,565 total health-based violations recorded. The most affected states are New York, Connecticut, California.
Selenium 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, SDWIS records show 1,565 health-based violations for Selenium affecting 197 community water systems in 5 states. Violation counts cluster heaviest in New York, Connecticut, California, with New York alone accounting for 532 violations across 48 systems. The contaminant is listed on the federal primary drinking water regulations.
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.
Violations by State
States ranked by number of health-based violations for Selenium.
| # | State | Violations | Systems Affected |
|---|---|---|---|
| 1 | New York | 532 | 48 |
| 2 | Connecticut | 42 | 1 |
| 3 | California | 30 | 1 |
| 4 | Delaware | 2 | 1 |
| 5 | North Carolina | 2 | 1 |
Most Affected Water Systems
Top 50 water systems by number of Selenium health-based violations.
Frequently Asked Questions
Is Selenium in my water?
Selenium has been detected in violation of EPA health standards in 197 water systems across 5 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 Selenium violations?
EPA SDWIS records show 197 community water systems with health-based Selenium violations, totaling 1,565 violations. These represent cases where the contaminant exceeded the EPA Maximum Contaminant Level (MCL).
Which states have the most Selenium violations?
The states with the most Selenium violations are: New York (532 violations), Connecticut (42 violations), California (30 violations), Delaware (2 violations), North Carolina (2 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 U.S. Environmental Protection Agency, SDWIS Federal Reporting Services
Read our methodology - how this data is sourced, computed, and verified.