Bromoform

Castle Rock

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

MORE ABOUT THIS CONTAMINANT

113

Samples

Samples exceeding legal limit (MCL)

Samples exceeding
health guidelines

Testing results - average by year

Year	Average result	Samples taken	Detections	Range of results
2014	N/A	0	0	N/A
2015	ND	1	0	ND
2016	0.223 ppb	24	3	ND - 3.01 ppb
2017	0.993 ppb	24	8	ND - 7.49 ppb
2018	2.35 ppb	32	19	ND - 7.20 ppb
2019	0.794 ppb	32	11	ND - 4.10 ppb

ppb = parts per billion

State and national drinking water standards and health guidelines

EWG Health Guideline 0.5 ppb

The EWG Health Guideline of 0.5 ppb for bromoform 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	Result
2015-03-24	ND
2016-05-03	ND
2016-05-03	ND
2016-05-03	1.34 ppb
2016-05-03	ND
2016-05-03	ND
2016-05-03	ND
2016-05-03	ND
2016-05-03	ND
2016-08-15	ND
2016-08-15	ND
2016-08-15	ND
2016-08-15	ND
2016-08-15	ND
2016-08-15	ND
2016-08-15	ND
2016-08-15	ND
2016-11-14	3.01 ppb
2016-11-14	ND
2016-11-14	1.000 ppb
2016-11-14	ND
2016-11-14	ND
2016-11-14	ND
2016-11-14	ND
2016-11-14	ND
2017-05-15	ND
2017-05-15	ND
2017-05-15	1.33 ppb
2017-05-15	ND
2017-05-15	ND
2017-05-15	ND
2017-05-15	ND
2017-05-16	ND
2017-08-15	ND
2017-08-15	ND
2017-08-15	ND
2017-08-15	0.870 ppb
2017-08-15	ND
2017-08-15	ND
2017-08-15	ND
2017-08-23	ND
2017-11-13	5.69 ppb
2017-11-13	ND
2017-11-13	7.49 ppb
2017-11-13	1.13 ppb
2017-11-13	0.840 ppb
2017-11-13	5.92 ppb
2017-11-13	ND
2017-11-13	0.550 ppb
2018-02-21	6.00 ppb
2018-02-21	6.30 ppb
2018-02-21	7.20 ppb
2018-02-21	ND
2018-02-21	ND
2018-02-21	3.40 ppb
2018-02-21	1.40 ppb
2018-02-21	6.00 ppb
2018-05-14	ND
2018-05-14	ND
2018-05-14	ND
2018-05-14	5.10 ppb
2018-05-14	4.30 ppb
2018-05-14	ND
2018-05-14	ND
2018-05-14	5.00 ppb
2018-08-07	2.30 ppb
2018-08-07	5.60 ppb
2018-08-07	2.80 ppb
2018-08-07	1.10 ppb
2018-08-07	ND
2018-08-07	1.10 ppb
2018-08-07	1.30 ppb
2018-08-07	1.90 ppb
2018-11-27	6.20 ppb
2018-11-27	ND
2018-11-27	3.10 ppb
2018-11-27	ND
2018-11-27	ND
2018-11-27	ND
2018-11-27	ND
2018-11-27	5.10 ppb
2019-02-19	3.70 ppb
2019-02-19	ND
2019-02-19	4.10 ppb
2019-02-19	ND
2019-02-19	ND
2019-02-19	ND
2019-02-19	0.600 ppb
2019-02-19	3.40 ppb
2019-05-07	ND
2019-05-07	ND
2019-05-07	2.30 ppb
2019-05-07	ND
2019-05-08	ND
2019-05-08	ND
2019-05-08	ND
2019-05-08	ND
2019-08-07	2.80 ppb
2019-08-07	ND
2019-08-07	1.80 ppb
2019-08-07	1.20 ppb
2019-08-07	ND
2019-08-07	ND
2019-08-07	1.10 ppb
2019-08-07	1.30 ppb
2019-11-12	ND
2019-11-12	ND
2019-11-12	3.10 ppb
2019-11-12	ND
2019-11-12	ND
2019-11-12	ND
2019-11-12	ND
2019-11-12	ND