Chloroform

City of Concord

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

195

Samples

Samples exceeding legal limit (MCL)

195

Samples exceeding
health guidelines

Testing results - average by year

Year	Average result	Samples taken	Detections	Range of results
2014	40.8 ppb	32	32	22.0 ppb - 63.0 ppb
2015	46.6 ppb	32	32	23.0 ppb - 81.0 ppb
2016	39.7 ppb	32	32	22.0 ppb - 96.0 ppb
2017	42.9 ppb	32	32	19.0 ppb - 96.0 ppb
2018	43.2 ppb	33	33	11.0 ppb - 84.0 ppb
2019	34.7 ppb	34	34	13.0 ppb - 62.0 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	Lab ID	Result
2014-02-19	8221-021914-B01M	27.0 ppb
2014-02-19	8221-021914-B02M	28.0 ppb
2014-02-19	8221-021914-B03M	27.0 ppb
2014-02-19	8221-021914-B04M	31.0 ppb
2014-02-19	8221-021914-B05M	27.0 ppb
2014-02-19	8221-021914-B06M	24.0 ppb
2014-02-19	8221-021914-B07M	31.0 ppb
2014-02-19	8221-021914-B08M	22.0 ppb
2014-05-14	8221-051414-B01M	54.0 ppb
2014-05-14	8221-051414-B02M	55.0 ppb
2014-05-14	8221-051414-B03M	53.0 ppb
2014-05-14	8221-051414-B04M	48.0 ppb
2014-05-14	8221-051414-B05M	44.0 ppb
2014-05-14	8221-051414-B06M	53.0 ppb
2014-05-14	8221-051414-B07M	56.0 ppb
2014-05-14	8221-051414-B08M	43.0 ppb
2014-08-06	8221-080614-B01M	45.0 ppb
2014-08-06	8221-080614-B02M	58.0 ppb
2014-08-06	8221-080614-B03M	61.0 ppb
2014-08-06	8221-080614-B04M	62.0 ppb
2014-08-06	8221-080614-B05M	45.0 ppb
2014-08-06	8221-080614-B06M	50.0 ppb
2014-08-06	8221-080614-B07M	63.0 ppb
2014-08-06	8221-080614-B08M	35.0 ppb
2014-11-12	8221-111214-B01M	44.0 ppb
2014-11-12	8221-111214-B02M	29.0 ppb
2014-11-12	8221-111214-B03M	29.0 ppb
2014-11-12	8221-111214-B04M	30.0 ppb
2014-11-12	8221-111214-B05M	32.0 ppb
2014-11-12	8221-111214-B06M	31.0 ppb
2014-11-12	8221-111214-B07M	41.0 ppb
2014-11-12	8221-111214-B08M	27.0 ppb
2015-02-11		33.0 ppb
2015-02-11		24.0 ppb
2015-02-11		25.0 ppb
2015-02-11		26.0 ppb
2015-02-11		25.0 ppb
2015-02-11		23.0 ppb
2015-02-11		31.0 ppb
2015-02-11		30.0 ppb
2015-05-13		52.0 ppb
2015-05-13		81.0 ppb
2015-05-13		71.0 ppb
2015-05-13		59.0 ppb
2015-05-13		58.0 ppb
2015-05-13		60.0 ppb
2015-05-13		63.0 ppb
2015-05-20		69.0 ppb
2015-08-12		54.0 ppb
2015-08-12		44.0 ppb
2015-08-12		43.0 ppb
2015-08-12		56.0 ppb
2015-08-12		41.0 ppb
2015-08-12		72.0 ppb
2015-08-12		69.0 ppb
2015-08-12		44.0 ppb
2015-11-11		40.0 ppb
2015-11-11		36.0 ppb
2015-11-11		36.0 ppb
2015-11-11		47.0 ppb
2015-11-11		41.0 ppb
2015-11-11		34.0 ppb
2015-11-11		56.0 ppb
2015-11-11		48.0 ppb
2016-02-09	3398142	28.0 ppb
2016-02-09	3398143	28.0 ppb
2016-02-09	3398144	33.0 ppb
2016-02-09	3398145	32.0 ppb
2016-02-09	3398146	24.0 ppb
2016-02-09	3398147	30.0 ppb
2016-02-09	3398148	30.0 ppb
2016-02-09	3398149	36.0 ppb
2016-05-10	3445891	39.0 ppb
2016-05-10	3445892	25.0 ppb
2016-05-10	3445893	24.0 ppb
2016-05-10	3445894	31.0 ppb
2016-05-10	3445895	32.0 ppb
2016-05-10	3445896	22.0 ppb
2016-05-10	3445897	38.0 ppb
2016-05-10	3445898	38.0 ppb
2016-08-09	3516964	71.0 ppb
2016-08-09	3516965	45.0 ppb
2016-08-09	3516966	47.0 ppb
2016-08-09	3516967	62.0 ppb
2016-08-09	3516968	69.0 ppb
2016-08-09	3516969	51.0 ppb
2016-08-09	3516970	96.0 ppb
2016-08-09	3516971	52.0 ppb
2016-11-08	3582281	49.0 ppb
2016-11-08	3582282	33.0 ppb
2016-11-08	3582283	29.0 ppb
2016-11-08	3582284	29.0 ppb
2016-11-08	3582285	38.0 ppb
2016-11-08	3582286	23.0 ppb
2016-11-08	3582287	52.0 ppb
2016-11-08	3582288	35.0 ppb
2017-02-14	3638203	33.0 ppb
2017-02-14	3638204	20.0 ppb
2017-02-14	3638205	19.0 ppb
2017-02-14	3638206	21.0 ppb
2017-02-14	3638207	31.0 ppb
2017-02-14	3638208	19.0 ppb
2017-02-14	3638209	41.0 ppb
2017-02-14	3638210	29.0 ppb
2017-05-09	3691007	51.0 ppb
2017-05-09	3691008	30.0 ppb
2017-05-09	3691009	30.0 ppb
2017-05-09	3691010	39.0 ppb
2017-05-09	3691011	52.0 ppb
2017-05-09	3691012	32.0 ppb
2017-05-09	3691013	69.0 ppb
2017-05-09	3691014	43.0 ppb
2017-08-08	3751651	96.0 ppb
2017-08-08	3751652	60.0 ppb
2017-08-08	3751653	56.0 ppb
2017-08-08	3751654	72.0 ppb
2017-08-08	3751655	65.0 ppb
2017-08-08	3751656	74.0 ppb
2017-08-08	3751657	62.0 ppb
2017-08-08	3751658	76.0 ppb
2017-11-16	3823064	33.0 ppb
2017-11-16	3823065	29.0 ppb
2017-11-16	3823066	28.0 ppb
2017-11-16	3823067	20.0 ppb
2017-11-16	3823068	21.0 ppb
2017-11-16	3823069	31.0 ppb
2017-11-16	3823070	47.0 ppb
2017-11-16	3823071	43.0 ppb
2018-02-13	3871444	22.0 ppb
2018-02-13	3871445	25.0 ppb
2018-02-13	3871446	26.0 ppb
2018-02-13	3871447	15.0 ppb
2018-02-13	3871448	11.0 ppb
2018-02-13	3871449	25.0 ppb
2018-02-13	3871450	19.0 ppb
2018-02-13	3871451	35.0 ppb
2018-05-08	3931391	39.0 ppb
2018-05-08	3931392	52.0 ppb
2018-05-08	3931393	53.0 ppb
2018-05-08	3931394	36.0 ppb
2018-05-08	3931395	25.0 ppb
2018-05-08	3931396	56.0 ppb
2018-05-08	3931397	38.0 ppb
2018-05-08	3931398	67.0 ppb
2018-05-24	3946294	58.0 ppb
2018-08-21	4031486	78.0 ppb
2018-08-21	4031487	49.0 ppb
2018-08-21	4031488	47.0 ppb
2018-08-21	4031489	66.0 ppb
2018-08-21	4031490	57.0 ppb
2018-08-21	4031491	53.0 ppb
2018-08-21	4031492	67.0 ppb
2018-08-21	4031493	84.0 ppb
2018-11-13	4121274	40.0 ppb
2018-11-13	4121276	48.0 ppb
2018-11-13	4121278	52.0 ppb
2018-11-13	4121353	43.0 ppb
2018-11-13	4121355	39.0 ppb
2018-11-13	4121357	37.0 ppb
2018-11-13	4121359	27.0 ppb
2018-11-13	4121361	38.0 ppb
2019-02-04	4187564	21.0 ppb
2019-02-04	4187620	18.0 ppb
2019-02-12	4195480-1	21.0 ppb
2019-02-12	4195481-1	22.0 ppb
2019-02-12	4195482-1	21.0 ppb
2019-02-12	4195483-1	15.0 ppb
2019-02-12	4195484-1	13.0 ppb
2019-02-12	4195485-1	22.0 ppb
2019-02-12	4195486-1	21.0 ppb
2019-02-12	4195487-1	26.0 ppb
2019-05-14	4294422	26.0 ppb
2019-05-14	4294424	37.0 ppb
2019-05-14	4294426	38.0 ppb
2019-05-14	4294428	28.0 ppb
2019-05-14	4294430	19.0 ppb
2019-05-14	4294432	40.0 ppb
2019-05-14	4294434	25.0 ppb
2019-05-14	4294436	41.0 ppb
2019-08-13	4385972	59.0 ppb
2019-08-13	4385974	50.0 ppb
2019-08-13	4385976	49.0 ppb
2019-08-13	4385978	55.0 ppb
2019-08-13	4385980	39.0 ppb
2019-08-13	4385982	53.0 ppb
2019-08-13	4385984	50.0 ppb
2019-08-13	4385986	62.0 ppb
2019-11-12	4483517	42.0 ppb
2019-11-12	4483519	39.0 ppb
2019-11-12	4483521	39.0 ppb
2019-11-12	4483523	31.0 ppb
2019-11-12	4483525	25.0 ppb
2019-11-12	4483527	46.0 ppb
2019-11-12	4483529	41.0 ppb
2019-11-12	4483531	46.0 ppb