Disinfection byproducts · 2025
TTHM in Columbus, OH tap water
Columbus, OH's 2025 Consumer Confidence Report shows TTHM at or above the federal limit (0.08 MCL). Measured value is 1.0× the threshold.
The measurement
| Statistic | Value | Federal limit |
|---|---|---|
Reported level Dublin Road Water Plant | 58.4 ug/L | None set |
Range Dublin Road Water Plant | 16.5–83.9 ug/L | None set |
Reported level Hap Cremean Water Plant | 64.1 ug/L | None set |
Range Hap Cremean Water Plant | 22.8–60.3 ug/L | None set |
Reported level Parsons Avenue Water Plant | 27.6 ug/L | None set |
Range Parsons Avenue Water Plant | 22.3–34.2 ug/L | None set |
Reported level Columbus Water | 0.038 | 0.08 MCL |
Verbatim from Columbus, OH's 2025 Consumer Confidence Report — source document ↗
About TTHM
Total trihalomethanes — a group of four chemicals (including chloroform) formed when chlorine reacts with natural organic matter.
Long-term exposure above the federal limit is linked to liver, kidney, and central-nervous-system effects and increased cancer risk.
How Columbus, OH compares
5 of the 1176 systems measuring TTHM on The Water Map have it at or above the federal limit:
Nearby systems also reporting TTHM:
People also ask
+Is there TTHM in Columbus, OH tap water?
Yes — Columbus, OH's 2025 Consumer Confidence Report lists TTHM at 16.5–83.9 ug/L. Columbus, OH's 2025 Consumer Confidence Report shows TTHM at or above the federal limit (0.08 MCL). Measured value is 1.0× the threshold.
+What's the federal limit for TTHM in drinking water?
The federal MCL for TTHM is 0.08 . The EPA enforces this against the regulated reporting statistic (running annual average or 90th percentile), not a single-sample spike.
+What is TTHM?
Total trihalomethanes — a group of four chemicals (including chloroform) formed when chlorine reacts with natural organic matter. Long-term exposure above the federal limit is linked to liver, kidney, and central-nervous-system effects and increased cancer risk.
+Which other U.S. cities have TTHM over the federal limit?
5 of the 1176 systems on The Water Map measuring TTHM report it at or above the federal limit. Examples include Jackson, MS, Pittsburgh, PA, Freedom District, MD.
+Where does this TTHM measurement come from?
This page reproduces the TTHM entry from the 2025 Consumer Confidence Report published by the Columbus, OH water utility — the annual drinking-water report every U.S. utility is required by federal law to publish. The original source document is archived at /water/oh/columbus/2025/source.