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
20120.713 ppb12120.510 ppb - 0.920 ppb
20130.731 ppb1615ND - 1.04 ppb
20140.648 ppb1613ND - 1.12 ppb
20150.889 ppb108ND - 1.94 ppb
20160.876 ppb880.610 ppb - 1.41 ppb
20170.809 ppb880.670 ppb - 1.06 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
2012-04-17AB691100.670 ppb
2012-04-17AB691110.670 ppb
2012-04-17AB691120.640 ppb
2012-04-17AB691130.760 ppb
2012-07-24AB781070.920 ppb
2012-07-24AB781060.860 ppb
2012-07-24AB781050.910 ppb
2012-07-24AB781040.900 ppb
2012-10-23AB848330.510 ppb
2012-10-23AB848320.550 ppb
2012-10-23AB848310.560 ppb
2012-10-23AB848300.600 ppb
2013-01-24AB898180.850 ppb
2013-01-24AB898190.640 ppb
2013-01-24AB898200.580 ppb
2013-01-24AB898210.630 ppb
2013-04-16AB948890.560 ppb
2013-04-16AB948880.560 ppb
2013-04-16AB948870.520 ppb
2013-07-18AC053390.970 ppb
2013-07-18AC053400.990 ppb
2013-07-18AC053411.01 ppb
2013-07-18AC053421.04 ppb
2013-10-14AC125530.830 ppb
2013-10-14AC125520.780 ppb
2013-10-14AC125510.880 ppb
2013-10-14AC125500.860 ppb
2014-01-14AC165830.550 ppb
2014-04-07AC214910.730 ppb
2014-04-07AC214900.710 ppb
2014-04-07AC214890.810 ppb
2014-04-07AC214880.910 ppb
2014-07-22AC304731.12 ppb
2014-07-22AC304740.920 ppb
2014-07-22AC304751.000 ppb
2014-07-22AC304760.940 ppb
2014-10-14AC375650.640 ppb
2014-10-14AC375640.640 ppb
2014-10-14AC375630.750 ppb
2014-10-14AC375620.640 ppb
2015-01-16AC402860.540 ppb
2015-01-16AC402880.560 ppb
2015-04-20AC449770.800 ppb
2015-04-20AC449760.820 ppb
2015-07-14AC541711.94 ppb
2015-07-14AC541721.93 ppb
2015-10-21AC611351.18 ppb
2015-10-21AC611341.12 ppb
2016-01-12AC649360.620 ppb
2016-01-12AC649370.610 ppb
2016-04-25AC692970.760 ppb
2016-04-25AC692960.820 ppb
2016-07-12AC796411.32 ppb
2016-07-12AC796401.41 ppb
2016-10-18AC862070.760 ppb
2016-10-18AC862060.710 ppb
2017-01-09AC890170.670 ppb
2017-01-09AC890180.690 ppb
2017-04-11AC943840.700 ppb
2017-04-11AC943850.680 ppb
2017-07-11AD012861.05 ppb
2017-07-11AD012871.06 ppb
2017-10-17AD078230.780 ppb
2017-10-17AD078220.840 ppb