Disinfection byproducts
Chloroform in U.S. tap water
56 public water systems across 13 U.S. states report Chloroform in their annual Consumer Confidence Report. 1 sit at or above the federal limit.
What it is
A trihalomethane formed when chlorine reacts with organic matter in water.
Why it's regulated
A component of regulated total trihalomethanes; long-term exposure is linked to liver and kidney effects.
At or above the federal limit (1)
| Water system | Measured | vs. limit |
|---|---|---|
| Pomona, CA 2024 annual report | 0–11 ug/L | 11.0× the limit |
Within the federal limit (10)
| Water system | Measured |
|---|---|
| Birmingham, AL 2024 annual report | 8.84–19 |
| Overland Park, KS 2023 annual report | 18.3 |
| Austin, TX 2024 annual report | 14.1 ug/L |
| Dallas, TX 2024 annual report | 10.22 ug/L |
| Georgetown, TX 2024 annual report | 8.7 ug/L |
| Fort Worth, TX 2024 annual report | 3.3 ug/L |
| Lewisville, TX 2024 annual report | 3.17 ug/L |
| Cambridge, MA 2024 annual report | 1.7 mg/L |
| Charleston, SC 2024 annual report | 7.2 ug/L |
| North Charleston, SC 2024 annual report | 7.2 ug/L |
Frequently asked
+What is Chloroform?
A trihalomethane formed when chlorine reacts with organic matter in water. A component of regulated total trihalomethanes; long-term exposure is linked to liver and kidney effects.
+What is the federal limit for Chloroform in drinking water?
The federal MCLG for Chloroform is 70 ug/L. The EPA enforces this against the regulated reporting statistic (typically a running annual average or 90th percentile), not a single-sample spike.
+How many U.S. water systems have Chloroform over the federal limit?
1 of the 56 public water systems on The Water Map report Chloroform at or above its federal limit, spanning 13 U.S. states. The full list is on this page.
+How can I check if Chloroform is in my city's tap water?
Search your city on The Water Map (https://www.thewatermap.com/) or browse the list on this page. Every U.S. public water utility is required to publish an annual Consumer Confidence Report that lists every contaminant it measured, including Chloroform.