Chloroform

Acton Water Supply District

Chloroform, one of the total trihalomethanes (TTHMs), is formed when chlorine or other disinfectants are used to treat drinking water. Chloroform and other disinfection byproducts increase the risk of cancer and may cause problems during pregnancy. Read More.

In addition to tap water disinfection, chloroform pollution in the environment also comes from industrial discharges from pulp and paper mills, and from urban wastewater effluent. Human studies show that chloroform damages the kidneys, liver and central nervous system. In animals, chloroform causes infertility, birth defects and cancer.

Click here to read more about disinfection byproducts.

MORE ABOUT THIS CONTAMINANT

183

Samples

Samples exceeding legal limit (MCL)

110

Samples exceeding
health guidelines

Testing results - average by year

Year	Average result	Samples taken	Detections	Range of results
2013	N/A	0	0	N/A
2014	0.697 ppb	19	2	ND - 11.0 ppb
2015	8.13 ppb	32	20	ND - 58.6 ppb
2016	6.65 ppb	34	22	ND - 53.6 ppb
2017	5.64 ppb	33	22	ND - 62.0 ppb
2018	12.8 ppb	31	22	ND - 78.2 ppb
2019	9.28 ppb	34	22	ND - 65.9 ppb

ppb = parts per billion

State and national drinking water standards and health guidelines

EWG Health Guideline 0.4 ppb

The EWG Health Guideline of 0.4 ppb for chloroform 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
2014-02-20	ND
2014-05-19	ND
2014-07-16	ND
2014-07-16	ND
2014-07-16	ND
2014-08-04	ND
2014-08-04	ND
2014-08-04	ND
2014-08-04	ND
2014-08-04	ND
2014-08-04	ND
2014-08-04	ND
2014-08-15	ND
2014-08-15	11.0 ppb
2014-08-15	ND
2014-08-15	2.24 ppb
2014-08-15	ND
2014-08-26	ND
2014-10-20	ND
2015-02-18	25.2 ppb
2015-02-18	ND
2015-02-18	0.780 ppb
2015-02-19	2.17 ppb
2015-05-22	30.4 ppb
2015-05-22	ND
2015-05-22	1.41 ppb
2015-05-22	1.23 ppb
2015-06-26	2.10 ppb
2015-08-03	ND
2015-08-03	52.0 ppb
2015-08-03	ND
2015-08-03	2.40 ppb
2015-08-03	ND
2015-08-17	1.92 ppb
2015-08-17	ND
2015-08-17	ND
2015-08-17	ND
2015-08-17	0.510 ppb
2015-08-17	ND
2015-08-19	50.5 ppb
2015-08-19	3.38 ppb
2015-08-19	4.52 ppb
2015-08-19	4.41 ppb
2015-09-14	ND
2015-09-14	ND
2015-09-14	ND
2015-11-18	7.84 ppb
2015-11-18	3.65 ppb
2015-11-19	58.6 ppb
2015-11-19	6.57 ppb
2015-11-30	0.600 ppb
2016-02-10	ND
2016-02-17	3.82 ppb
2016-02-17	3.25 ppb
2016-02-17	2.45 ppb
2016-02-17	3.37 ppb
2016-05-17	53.6 ppb
2016-05-17	1.40 ppb
2016-05-17	2.83 ppb
2016-05-17	6.37 ppb
2016-06-06	ND
2016-07-14	33.0 ppb
2016-07-25	ND
2016-07-29	ND
2016-07-29	0.600 ppb
2016-07-29	ND
2016-08-08	16.0 ppb
2016-08-16	21.0 ppb
2016-08-16	5.54 ppb
2016-08-16	2.37 ppb
2016-08-16	2.63 ppb
2016-09-07	0.990 ppb
2016-09-07	ND
2016-09-07	ND
2016-09-07	ND
2016-09-07	0.660 ppb
2016-09-07	ND
2016-09-22	ND
2016-09-22	ND
2016-09-22	ND
2016-11-15	3.99 ppb
2016-11-15	13.5 ppb
2016-11-16	45.6 ppb
2016-11-16	2.44 ppb
2016-11-17	0.700 ppb
2017-02-01	0.620 ppb
2017-02-15	24.1 ppb
2017-02-15	1.60 ppb
2017-02-15	1.69 ppb
2017-02-15	8.33 ppb
2017-05-03	0.800 ppb
2017-05-17	62.0 ppb
2017-05-17	3.69 ppb
2017-05-17	5.15 ppb
2017-05-17	8.84 ppb
2017-07-12	ND
2017-07-12	ND
2017-07-12	ND
2017-07-27	ND
2017-07-27	1.30 ppb
2017-08-09	2.70 ppb
2017-08-09	ND
2017-08-09	ND
2017-08-09	ND
2017-08-09	0.600 ppb
2017-08-09	ND
2017-08-16	7.38 ppb
2017-08-16	2.14 ppb
2017-08-16	7.52 ppb
2017-08-16	12.3 ppb
2017-11-16	8.08 ppb
2017-11-16	7.63 ppb
2017-11-16	8.73 ppb
2017-11-17	9.55 ppb
2017-12-11	ND
2017-12-11	1.31 ppb
2017-12-11	ND
2017-12-11	ND
2018-02-12	3.55 ppb
2018-02-12	3.77 ppb
2018-02-12	2.26 ppb
2018-02-12	4.77 ppb
2018-03-14	1.22 ppb
2018-05-16	9.94 ppb
2018-05-16	5.84 ppb
2018-05-16	12.7 ppb
2018-05-16	20.2 ppb
2018-06-11	4.43 ppb
2018-07-26	60.0 ppb
2018-07-26	ND
2018-07-26	1.10 ppb
2018-08-15	69.4 ppb
2018-08-15	11.3 ppb
2018-08-15	40.3 ppb
2018-08-15	18.6 ppb
2018-09-05	ND
2018-09-05	ND
2018-09-05	ND
2018-09-19	6.60 ppb
2018-09-19	ND
2018-09-19	ND
2018-09-19	ND
2018-09-19	ND
2018-09-19	ND
2018-11-20	78.2 ppb
2018-11-20	17.1 ppb
2018-11-20	10.1 ppb
2018-11-20	14.4 ppb
2018-12-10	2.32 ppb
2019-02-21	16.8 ppb
2019-02-21	2.10 ppb
2019-02-21	1.77 ppb
2019-02-21	2.70 ppb
2019-03-26	1.40 ppb
2019-05-14	4.48 ppb
2019-05-15	8.35 ppb
2019-05-15	12.3 ppb
2019-05-15	14.2 ppb
2019-05-15	20.9 ppb
2019-07-24	ND
2019-07-24	ND
2019-07-25	ND
2019-07-25	27.5 ppb
2019-07-25	ND
2019-07-25	1.06 ppb
2019-07-31	ND
2019-07-31	ND
2019-08-21	65.9 ppb
2019-08-21	13.0 ppb
2019-08-21	20.8 ppb
2019-08-21	23.2 ppb
2019-09-10	ND
2019-09-16	5.05 ppb
2019-09-16	ND
2019-09-16	ND
2019-09-16	ND
2019-09-16	ND
2019-09-16	ND
2019-11-21	34.7 ppb
2019-11-21	10.3 ppb
2019-11-21	7.86 ppb
2019-11-21	18.1 ppb
2019-12-11	2.90 ppb