EPA legal limit
No federal limit
Maximum Contaminant Level
EWG health guideline
0.6 ppb
Science-based, stricter target
IARC classification
Group 2B — possibly carcinogenic to humans
Cancer research classification
Health effects
DBCM is classified as possibly carcinogenic to humans (Group 2B) by IARC. Animal studies have demonstrated liver and kidney effects. Its EWG health guideline (0.6 ppb) is less strict than chloroform or BDCM, reflecting lower carcinogenic potency per unit concentration — but it is still commonly detected at levels exceeding the guideline in chlorinated water supplies.
Where it comes from
Forms during chlorination when bromide naturally present in source water reacts with chlorine. More prevalent in coastal utilities and water drawn from sources with elevated bromide. Formation increases with higher organic matter content and warmer water temperature.
How it's regulated
No individual EPA MCL — regulated under the TTHM group standard of 80 ppb. EWG health guideline: 0.6 ppb, based on cancer risk assessment. Typically detected at lower levels than chloroform and BDCM.
How to filter dibromochloromethane
Not all filters address dibromochloromethane. Look for independently certified filters — NSF International certification means the removal claim has been independently verified.
Frequently asked questions
What is dibromochloromethane?
Dibromochloromethane (DBCM) is a trihalomethane compound that forms when chlorine disinfects water containing higher bromide concentrations. It is typically the third most prevalent TTHM compound, present at lower levels than chloroform and BDCM but still contributing meaningfully to total TTHM exposure.
What are the health effects of dibromochloromethane?
DBCM is classified as possibly carcinogenic to humans (Group 2B) by IARC. Animal studies have demonstrated liver and kidney effects. Its EWG health guideline (0.6 ppb) is less strict than chloroform or BDCM, reflecting lower carcinogenic potency per unit concentration — but it is still commonly detected at levels exceeding the guideline in chlorinated water supplies.
Is dibromochloromethane regulated in drinking water?
No individual EPA MCL — regulated under the TTHM group standard of 80 ppb. EWG health guideline: 0.6 ppb, based on cancer risk assessment. Typically detected at lower levels than chloroform and BDCM.
Where does dibromochloromethane come from?
Forms during chlorination when bromide naturally present in source water reacts with chlorine. More prevalent in coastal utilities and water drawn from sources with elevated bromide. Formation increases with higher organic matter content and warmer water temperature.
How do I remove dibromochloromethane from tap water?
The most effective methods for removing dibromochloromethane are: Activated carbon block filter, NSF 53 certified filter, Reverse osmosis (RO). Look for NSF-certified systems — independent certification confirms removal claims have been verified.
Is dibromochloromethane in your water?
Enter your ZIP code to see the measured level in your specific utility.