Chlorobenzene in drinking water
1,945 active public water systems in 42 states had a Chlorobenzene violation in the past three years, and 86 had one in the latest quarter of EPA's data.
You are on Tapcensus, an independent guide to the EPA compliance records of every public water system in the United States. This page explains Chlorobenzene and lists the water systems whose records include a related violation. It does not show measured levels.
Is Chlorobenzene in the records for your water system?
Enter a ZIP code, town, or street address to see the water systems that serve your area, their status, and which rules and contaminants appear in their violations.
Enter a ZIP code, town, or street address.
What it is and where it comes from
Chlorobenzene is an aromatic solvent and chemical intermediate used in the production of DDT, nitrochlorobenzenes, and other industrial chemicals. It enters drinking water through discharge from chemical manufacturing facilities and leaching from contaminated industrial sites. It is moderately volatile and moderately persistent in groundwater.
Health effects
Chronic exposure to chlorobenzene is associated with liver and kidney effects in animal studies. EPA has not classified it as a human carcinogen based on available data. Short-term exposure at high levels can cause nervous system depression. Long-term exposure above the MCL is the primary concern for public water system violations.
The standard and what a violation means
EPA limit: 0.1 mg/L (100 ppb).
Water systems with a Chlorobenzene violation, by state
Active public water systems that reported at least one related violation to EPA in the past three years. Each state links to the list of its affected systems.
| State | Systems with violations, 3 yr | Share of active systems | In violation, latest quarter |
|---|---|---|---|
| Illinois | 196 | 4% | 10 |
| Texas | 172 | 2% | 0 |
| Pennsylvania | 169 | 2% | 6 |
| Michigan | 165 | 1% | 4 |
| Alaska | 102 | 8% | 5 |
| Washington | 102 | 2% | 10 |
| Oregon | 85 | 3% | 3 |
| New Jersey | 77 | 2% | 5 |
| New York | 73 | 1% | 2 |
| Oklahoma | 71 | 5% | 0 |
| Colorado | 69 | 3% | 4 |
| Indiana | 66 | 2% | 3 |
| Idaho | 48 | 2% | 3 |
| Wisconsin | 45 | 0% | 5 |
| Montana | 40 | 2% | 0 |
| Connecticut | 39 | 2% | 4 |
| West Virginia | 38 | 5% | 1 |
| Missouri | 34 | 1% | 2 |
| Arizona | 33 | 2% | 3 |
| Virginia | 31 | 1% | 2 |
| Wyoming | 31 | 4% | 1 |
| Vermont | 30 | 2% | 3 |
| California | 29 | 0% | 2 |
| North Carolina | 26 | 1% | 1 |
| Nevada | 26 | 4% | 0 |
| Utah | 26 | 2% | 1 |
| Alabama | 18 | 3% | 0 |
| Maine | 18 | 1% | 0 |
| Iowa | 14 | 1% | 0 |
| Ohio | 14 | 0% | 1 |
| Massachusetts | 12 | 1% | 0 |
| Tennessee | 11 | 1% | 0 |
| Rhode Island | 9 | 2% | 1 |
| Minnesota | 7 | 0% | 1 |
| New Hampshire | 4 | 0% | 1 |
| Kansas | 3 | 0% | 0 |
| Mississippi | 3 | 0% | 1 |
| New Mexico | 3 | 0% | 0 |
| Maryland | 2 | 0% | 0 |
| South Dakota | 2 | 0% | 0 |
| Kentucky | 1 | 0% | 0 |
| North Dakota | 1 | 0% | 1 |
Largest water systems with a Chlorobenzene violation
The ten biggest systems, by people served, whose records include a related violation in the past three years.
| System | Serves | Status | Rules violated, 3 yr | Unresolved |
|---|---|---|---|---|
|
Tucson City of Tucson · Pima County |
732,906 | 3 | 0 | |
|
Mesa City of Mesa · Maricopa County |
466,000 | 3 | 0 | |
|
Chandler City of Chandler · Maricopa County |
247,328 | 4 | 0 | |
|
Trenton Water Works Ewing Twp, Hamilton Twp, Hopewell Twp.1106- and 2 more · Mercer County |
217,000 | 8 | 2 | |
|
Corona, City of Corona · Riverside County |
169,380 | 6 | 0 | |
|
City of Sunnyvale Sunnyvale · Santa Clara County |
157,566 | 5 | 0 | |
|
Sandy City Water System Salt Lake County |
99,750 | 2 | 0 | |
|
Epcor San Tan Johnson Ranch · Pinal County |
87,435 | 3 | 0 | |
|
Flagstaff City of Flagstaff · Coconino County |
79,796 | 5 | 0 | |
|
East Orange Water Commission East Orange City · Essex County |
75,000 | 6 | 1 |
About this data
A system is counted once if any of its violations in the past three years involved Chlorobenzene, including monitoring and reporting lapses. Rules violated and status in the systems table are for the whole system, not Chlorobenzene alone. Counts cover active systems in all 50 states and the District of Columbia.
Source: the U.S. EPA's Enforcement and Compliance History Online system (ECHO), which publishes the federal Safe Drinking Water Information System. EPA's terms and values are shown as published. The records are from EPA's data refresh of Oct 7, 2026; EPA refreshes this data quarterly, and states report to EPA with a lag of three to six months, so the newest violations may not appear yet.