Chloroform
CHCl₃·Affects liver, kidneys, heart, reproductive
The single most common disinfection byproduct in chlorinated tap water. Forms when chlorine reacts with naturally-occurring organic matter.
CHCl₃
EPA limit
0.080 mg/L (combined THMs)
Most at risk
Long-term consumers, pregnant women, frequent shower users
Found in
City water
AquaOx filters
YesActivated coconut shell carbon
What it does to you
Health effects
Chloroform is the dominant member of the trihalomethane (THM) family, which the EPA regulates as a group because they all behave similarly: classified as a probable human carcinogen, linked in long-term studies to elevated rates of bladder and colon cancer, and associated with adverse reproductive outcomes including low birth weight and miscarriage.
The liver and kidneys are the primary target organs for chronic chloroform exposure. Some epidemiological work also suggests a cardiovascular signal at sustained moderate exposure levels.
Crucially, you don't only get chloroform from drinking the water. Hot showers vaporize THMs and you inhale them; warm bath water absorbs through skin. For frequent showerers in chlorinated municipalities, inhaled and dermal chloroform can exceed ingested chloroform.
Where it comes from
How it gets into your water
Chloroform forms inside the water-treatment process itself. When the chlorine your utility adds to disinfect the water encounters naturally-occurring organic matter (leaves, soil, algae), it reacts to form chloroform and the other THMs. The reaction continues as water sits in distribution pipes on the way to your tap, so levels are often higher at the end of the line than near the treatment plant.
Hot temperatures accelerate the reaction. THM levels in city water typically peak in late summer and early fall when source-water organic content is highest.
Chlorinated treatment plants
Reaction between chlorine and organic matter
Distribution pipes
Reaction continues during transit
Hot showers
Vaporizes into bathroom air
Find out for yourself
Is it in your water?
If your home is on a chlorinated municipal supply (most US cities), chloroform is in your water. Every utility tests THMs and reports the running annual average in their Consumer Confidence Report (CCR). The EPA regulates combined THMs at 80 ppb; well-run utilities run well below that, but levels vary by season and your location in the distribution network.
Well-water households generally do not have chloroform unless they shock-chlorinate their well periodically.
The fix
How AquaOx filters it
Chloroform is filtered efficiently by activated carbon, the centerpiece of every AquaOx system. Both the Centaur catalytic carbon and the coconut shell activated carbon stages capture THMs as water passes through, dropping levels by 95+% in independent testing.
Because AquaOx is whole-house, it filters THMs from your shower water too: that's the exposure route most people underestimate. If you've ever felt slightly headachy or dry-skinned after a long hot shower in a chlorinated city, that's the chloroform.
Explore more
Related contaminants
Disinfection byproducts
Bromodichloromethane
Disinfection byproducts
Dibromochloromethane
Disinfection byproducts
Bromoform
Disinfection byproducts
Trihalomethane (TTHM)
Disinfection byproducts
Haloacetic Acids (HAAS)
Treatment additives