Disinfection byproducts · 2025
TTHM in Phoenix, AZ tap water
Phoenix, AZ's 2025 TTHM level is between 80% and 100% of the federal limit (80 ug/L MCL) — measured but not in violation.
The measurement
| Statistic | Value | Federal limit |
|---|---|---|
Range Sample Results | 4–68 ug/L | 80 ug/L MCL |
Verbatim from Phoenix, AZ'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 Phoenix, AZ compares
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People also ask
+Is there TTHM in Phoenix, AZ tap water?
Yes — Phoenix, AZ's 2025 Consumer Confidence Report lists TTHM at 4–68 ug/L. Phoenix, AZ's 2025 TTHM level is between 80% and 100% of the federal limit (80 ug/L MCL) — measured but not in violation.
+What's the federal limit for TTHM in drinking water?
The federal MCL for TTHM is 80 ug/L. 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.
+Where does this TTHM measurement come from?
This page reproduces the TTHM entry from the 2025 Consumer Confidence Report published by the Phoenix, AZ 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/az/phoenix/2025/source.