EWG's Tap Water Database — 2019 UPDATE




Bromodichloromethane, one of the total trihalomethanes (TTHMs), is formed when chlorine or other disinfectants are used to treat drinking water. Bromodichloromethane and other disinfection byproducts increase the risk of cancer and may cause problems during pregnancy. Click here to read more about disinfection byproducts.





Samples exceeding legal limit (MCL)


Samples exceeding
health guidelines

Testing results - average by year

YearAverage resultSamples takenDetectionsRange of results
20120.687 ppb12120.540 ppb - 0.910 ppb
20130.643 ppb1613ND - 1.12 ppb
20140.714 ppb16160.500 ppb - 1.13 ppb
20150.778 ppb107ND - 1.80 ppb
20160.901 ppb880.640 ppb - 1.38 ppb
20170.961 ppb880.720 ppb - 1.24 ppb

ppb = parts per billion

State and national drinking water standards and health guidelines

EWG Health Guideline 0.06 ppb

The EWG Health Guideline of 0.06 ppb for bromodichloromethane was proposed in 2018 by the California Office of Environmental Health Hazard Assessment as a one-in-a-million lifetime risk of cancer. Values greater than one-in-a-million cancer risk level can result in increased cancer cases above one in a million people.

ppb = parts per billion

All test results

Date Lab ID Result
2012-04-16AB691260.560 ppb
2012-04-16AB691270.650 ppb
2012-04-16AB691280.760 ppb
2012-04-16AB691290.630 ppb
2012-07-23AB781250.910 ppb
2012-07-23AB781270.880 ppb
2012-07-23AB781260.790 ppb
2012-07-23AB781240.830 ppb
2012-10-26AB848460.540 ppb
2012-10-26AB848470.580 ppb
2012-10-26AB848480.540 ppb
2012-10-26AB848490.570 ppb
2013-01-23AB898370.650 ppb
2013-01-23AB898350.630 ppb
2013-04-16AB949010.540 ppb
2013-04-16AB949020.550 ppb
2013-04-16AB949040.500 ppb
2013-07-18AC053610.960 ppb
2013-07-18AC053601.05 ppb
2013-07-18AC053591.03 ppb
2013-07-18AC053581.12 ppb
2013-10-17AC126170.870 ppb
2013-10-17AC126160.680 ppb
2013-10-17AC126150.760 ppb
2013-10-17AC126140.940 ppb
2014-01-10AC166650.600 ppb
2014-01-10AC166660.530 ppb
2014-01-10AC166670.590 ppb
2014-01-10AC166680.500 ppb
2014-04-02AC215750.680 ppb
2014-04-02AC215740.730 ppb
2014-04-02AC215730.730 ppb
2014-04-02AC215720.700 ppb
2014-07-23AC305890.890 ppb
2014-07-23AC305921.13 ppb
2014-07-31AC305900.870 ppb
2014-07-31AC305910.880 ppb
2014-10-20AC376340.700 ppb
2014-10-20AC376330.570 ppb
2014-10-20AC376320.660 ppb
2014-10-20AC376310.670 ppb
2015-01-20AC403580.550 ppb
2015-04-15AC450320.780 ppb
2015-04-15AC450310.750 ppb
2015-07-15AC542571.68 ppb
2015-07-15AC542561.80 ppb
2015-10-15AC611921.09 ppb
2015-10-15AC611931.13 ppb
2016-01-08AC649990.640 ppb
2016-01-08AC649980.700 ppb
2016-04-13AC693580.840 ppb
2016-04-13AC693570.810 ppb
2016-07-11AC796791.35 ppb
2016-07-11AC796801.38 ppb
2016-10-18AC862660.740 ppb
2016-10-18AC862650.750 ppb
2017-01-13AC890750.860 ppb
2017-01-13AC890760.930 ppb
2017-04-06AC944381.05 ppb
2017-04-06AC944371.04 ppb
2017-07-12AD013681.13 ppb
2017-07-12AD013691.24 ppb
2017-10-13AD078730.720 ppb
2017-10-13AD078740.720 ppb