Bromoform
CHBr₃·Affects liver, kidneys
The fully-brominated trihalomethane. Forms in chlorinated water that also contains naturally-occurring bromide, more common in coastal and saline source waters.
CHBr₃
EPA limit
0.080 mg/L (combined THMs)
Most at risk
Long-term consumers in coastal areas, frequent shower users, pregnant women
Found in
City water
AquaOx filters
YesActivated coconut shell carbon
What it does to you
Health effects
Bromoform is regulated under the EPA's Total Trihalomethane (TTHM) rule at 80 ppb in combination with chloroform, bromodichloromethane, and dibromochloromethane. The EPA classifies it as a probable human carcinogen, and long-term studies link THM exposure as a class to elevated bladder and colon cancer rates.
The liver and kidneys are the primary target organs for chronic bromoform exposure. Animal studies show liver tumors at sustained high doses, and human epidemiology associates the brominated THMs (bromoform, BDCM, DBCM) with adverse reproductive outcomes including low birth weight.
Like the other THMs, bromoform is volatile. Hot showers vaporize it into bathroom air, and warm bath water enables dermal absorption. For frequent showerers, inhaled plus dermal bromoform can exceed the dose from drinking the same water.
Where it comes from
How it gets into your water
Bromoform forms when chlorine added at the treatment plant reacts with naturally-occurring organic matter in the presence of bromide. Bromide is more abundant in coastal source waters, in groundwater affected by saltwater intrusion, and in some inland surface waters with mineral influences.
The more bromide in the source water, the further the THM mix shifts toward the brominated end. The reaction continues during distribution, so households at the periphery of the network often see higher brominated-THM levels than households near the treatment plant.
Chlorinated treatment plants
Chlorine reacts with organic matter + bromide
Distribution pipes
Reaction continues during transit
Hot showers
Vaporizes into bathroom air
Find out for yourself
Is it in your water?
Bromoform is typically a smaller fraction of total THMs than chloroform, except in coastal and high-bromide systems where the brominated species dominate. Your utility's annual Consumer Confidence Report (CCR) reports total THMs but often breaks out individual species too.
Levels rise in late summer and early fall when warmer water and higher organic loads accelerate the disinfection reaction. Households at the end of long distribution lines see the highest residuals.
The fix
How AquaOx filters it
Bromoform is captured efficiently by activated carbon. Both the catalytic and coconut-shell stages in AquaOx systems adsorb THMs as water passes through, and independent testing shows 95%+ filtration across the THM family.
Whole-house filtration is the meaningful difference: it filters bromoform from shower water, where inhalation and dermal absorption otherwise deliver a significant share of total exposure. Pitcher filters address the ingestion route but not the shower-vapor route.
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