Disinfection Byproduct
Total Trihalomethanes (TTHM) in your water
Is Total Trihalomethanes (TTHM) in drinking water dangerous?
It depends on the level and how long you're exposed. The EPA legal limit (MCL) for Total Trihalomethanes (TTHM) is 80 ppb. Meeting the legal limit isn't the same as zero risk — test your water to know your level.
How do you remove Total Trihalomethanes (TTHM) from water?
Total Trihalomethanes (TTHM) is treated by Reverse Osmosis and Whole-House Carbon Filter. Choose a system independently certified to NSF/ANSI standards to reduce Total Trihalomethanes (TTHM), and test your water first to confirm the level.
Source: EPA MCL / MCLG; WHO guidelines; NSF/ANSI · 2026
Health effects
TTHM form when chlorine used to disinfect water reacts with natural organic matter. Long-term exposure has been linked to increased cancer risk and to harm in pregnancy. Levels often rise in warmer months and in systems with more organic material. TTHM and haloacetic acids are the two main regulated groups of disinfection byproducts, which form whenever chlorine or similar disinfectants react with natural organic matter — an unavoidable trade-off of disinfecting water, though levels can be reduced.
The health-based goal vs. the legal limit
The federal legal limit (MCL) is the maximum allowed by law. The EPA health goal (MCLG) is the level below which no health risk is expected — it is non-enforceable and often stricter than the legal limit.
EPA health goal (MCLG)
No federal health goal set
Federal legal limit (MCL)
80 ppb
Source: EPA National Primary Drinking Water Regulations (MCL / MCLG) · 2026
What removes Total Trihalomethanes (TTHM)
Semipermeable membrane filtration
Reverse Osmosis
Pushes water through a fine membrane that removes the dissolved solids most filters miss.
Look for: NSF/ANSI 58 certification
How it works→Activated carbon adsorption
Whole-House Carbon Filter
A point-of-entry carbon bed that strips chlorine, chloramine, and chemical taste from every tap.
Look for: NSF/ANSI 42 certification
How it works→Where Total Trihalomethanes (TTHM) has been found
Total Trihalomethanes (TTHM) shows up in the public water record for these cities. Each page has the measured level, the legal limit, and what removes it.
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Is Total Trihalomethanes (TTHM) in your water?
Check your city's public record, then book a free 30-minute test to confirm what's in your home.