Chloroform in U.S. Drinking Water
Health-based violation data for Chloroform from EPA Safe Drinking Water Information System (SDWIS). Covers all community water systems with violations on record.
Chloroform has been found in violation of EPA standards in 330 water systems across 31 states, with 3,969 total health-based violations recorded. The most affected states are Oklahoma, New Mexico, Kansas.
Chloroform 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 3,969 health-based violations for Chloroform affecting 330 community water systems in 31 states. Violation counts cluster heaviest in Oklahoma, New Mexico, Kansas, with Oklahoma alone accounting for 1,591 violations across 77 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 Chloroform.
| # | State | Violations | Systems Affected |
|---|---|---|---|
| 1 | Oklahoma | 1,591 | 77 |
| 2 | New Mexico | 276 | 7 |
| 3 | Kansas | 217 | 20 |
| 4 | Idaho | 193 | 3 |
| 5 | Pennsylvania | 168 | 39 |
| 6 | West Virginia | 165 | 26 |
| 7 | Alaska | 153 | 6 |
| 8 | Illinois | 147 | 24 |
| 9 | Missouri | 121 | 10 |
| 10 | Louisiana | 117 | 12 |
| 11 | Puerto Rico | 89 | 8 |
| 12 | Montana | 85 | 2 |
| 13 | California | 77 | 10 |
| 14 | North Carolina | 65 | 8 |
| 15 | Arizona | 64 | 5 |
| 16 | Colorado | 35 | 8 |
| 17 | Kentucky | 31 | 10 |
| 18 | New York | 28 | 10 |
| 19 | Arkansas | 26 | 4 |
| 20 | Michigan | 25 | 6 |
| 21 | Indiana | 19 | 2 |
| 22 | Ohio | 18 | 1 |
| 23 | Maryland | 13 | 2 |
| 24 | New Hampshire | 11 | 1 |
| 25 | Georgia | 9 | 1 |
| 26 | Washington | 8 | 1 |
| 27 | Connecticut | 3 | 1 |
| 28 | Tennessee | 3 | 1 |
| 29 | Alabama | 2 | 1 |
| 30 | Oregon | 2 | 1 |
| 31 | Virginia | 2 | 1 |
Most Affected Water Systems
Top 50 water systems by number of Chloroform health-based violations.
Frequently Asked Questions
Is Chloroform in my water?
Chloroform has been detected in violation of EPA health standards in 330 water systems across 31 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 Chloroform violations?
EPA SDWIS records show 330 community water systems with health-based Chloroform violations, totaling 3,969 violations. These represent cases where the contaminant exceeded the EPA Maximum Contaminant Level (MCL).
Which states have the most Chloroform violations?
The states with the most Chloroform violations are: Oklahoma (1,591 violations), New Mexico (276 violations), Kansas (217 violations), Idaho (193 violations), Pennsylvania (168 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.