Total Trihalomethanes (TTHMs)
Category: disinfection byproduct
EPA MCL
0.08 mg/L
Status
EPA Regulated
NSF Standard
NSF/ANSI 53
Health Effects
Liver, kidney, and central nervous system problems. Increased risk of bladder and colorectal cancer with long-term exposure. Some trihalomethanes are probable human carcinogens.
Where It Comes From
Formed when chlorine used for disinfection reacts with naturally occurring organic matter (such as decaying leaves) in source water. The four TTHMs are chloroform, bromodichloromethane, dibromochloromethane, and bromoform.
Where It's Commonly Found
All chlorinated water systems produce some TTHMs. Higher levels in systems using surface water with high organic content, during warm months, and in water that travels long distances through the distribution system.
Found in virtually all chlorinated water systems. Thousands of systems have exceeded the EPA MCL. EWG health guideline of 0.15 ppb is far stricter than the EPA MCL of 80 ppb.
How to Remove It
Effective Technologies
- activated carbon
- carbon block
- reverse osmosis
Does NOT Remove It
- UV
- ion exchange
- water softener
- mechanical filtration
- ceramic
Filters That Address Total Trihalomethanes (TTHMs)
5 filters in our database list Total Trihalomethanes (TTHMs) reduction.
Aquasana Claryum 2-Stage (AQ-6200)
under sink
$124.99
$139.98/yr filters
Price checked Sep 2026
Aquasana Claryum 3-Stage Max Flow (AQ-6300M)
under sink
$224.99
$175.98/yr filters
Price checked Sep 2026
Waterdrop G3P800
under sink ro
$999
$166/yr filters
Price checked Sep 2026
Aquasana SmartFlow Reverse Osmosis
under sink ro
$159.99
$340/yr filters
Price checked Sep 2026
Aquasana HealthShield with Max Flow UV
whole house
$2898
Price checked Sep 2026
Official Sources
Related Contaminants
Learn More
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Enter Your ZIP Code →Informational guidance based on EPA data and NSF standards - not medical advice.