Dibromochloromethane
CHBr₂Cl·Affects liver, kidneys
A mixed bromine-chlorine trihalomethane. Forms in chlorinated water with moderate bromide content, and is regulated together with chloroform and the other THMs.
CHBr₂Cl
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
Dibromochloromethane (DBCM) is one of the four THMs regulated together at 80 ppb under the EPA's Stage 2 Disinfectants and Disinfection Byproducts Rule. It is classified as a possible human carcinogen, with the liver and kidneys as the primary target organs in long-term animal studies.
Human epidemiology links the brominated THMs (DBCM, BDCM, bromoform) more strongly than chloroform to adverse reproductive outcomes including low birth weight and pregnancy loss. The reproductive concern is one reason pregnant women are flagged as an at-risk group for THM exposure.
DBCM is volatile. Hot showers and warm baths transfer it into the air you breathe and through your skin. The combined inhalation + dermal dose can match or exceed the dose from drinking the same water.
Where it comes from
How it gets into your water
DBCM forms inside the treatment process when chlorine reacts with naturally-occurring organic matter in the presence of bromide. As bromide content rises, the THM mix shifts from chlorinated (chloroform) toward brominated (BDCM, DBCM, bromoform) species.
The reaction continues in distribution pipes on the way to your tap, so DBCM is generally higher at the end of the line than near the plant. Warm weather accelerates the formation, with levels peaking in late summer and early fall.
Chlorinated treatment plants
Chlorine reacts with organic matter + bromide
Distribution pipes
Reaction continues in transit
Hot showers
Vaporizes into bathroom air
Find out for yourself
Is it in your water?
Any chlorinated municipal supply with some bromide present will produce DBCM. Coastal cities, systems drawing from brackish sources, and utilities serving areas with saltwater intrusion typically see higher DBCM than inland systems. Your utility's annual Consumer Confidence Report (CCR) reports total THMs and often breaks out individual species.
Levels are typically highest in late summer and at the periphery of the distribution network.
The fix
How AquaOx filters it
Activated carbon captures DBCM efficiently. The catalytic and coconut-shell carbon stages in AquaOx systems adsorb the full THM family, with independent testing showing 95%+ reduction.
Because AquaOx is whole-house, DBCM is filtered before water reaches your shower head. That eliminates the inhalation and dermal exposure routes that pitcher filters cannot address.
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