Chloroform

City of Tracy

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

239

Samples

Samples exceeding legal limit (MCL)

206

Samples exceeding
health guidelines

Testing results - average by year

Year	Average result	Samples taken	Detections	Range of results
2014	15.7 ppb	46	40	ND - 39.0 ppb
2015	21.0 ppb	34	32	ND - 41.0 ppb
2016	28.1 ppb	40	33	ND - 65.0 ppb
2017	33.0 ppb	45	37	ND - 96.0 ppb
2018	21.4 ppb	41	33	ND - 68.0 ppb
2019	24.2 ppb	33	31	ND - 59.0 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
2014-01-27	9590-900-1049	29.0 ppb
2014-01-27	9590-901-0923	26.0 ppb
2014-01-27	9590-902-0904	26.0 ppb
2014-01-27	9590-903-1349	26.0 ppb
2014-01-27	9590-904-1408	16.0 ppb
2014-01-27	9590-905-1304	21.0 ppb
2014-01-27	9590-906-1334	26.0 ppb
2014-01-27	9590-907-0946	28.0 ppb
2014-04-07	9590-900-1058	39.0 ppb
2014-04-07	9590-901-1002	30.0 ppb
2014-04-07	9590-902-0945	25.0 ppb
2014-04-07	9590-903-1214	35.0 ppb
2014-04-07	9590-904-1253	16.0 ppb
2014-04-07	9590-905-1233	28.0 ppb
2014-04-07	9590-906-1038	34.0 ppb
2014-04-07	9590-907-1018	36.0 ppb
2014-04-28	9590-008-1408	20.0 ppb
2014-05-29	9590-008-0949	14.0 ppb
2014-06-16	9590-003-0802	ND
2014-06-16	9590-005-0732	ND
2014-06-16	9590-006-0745	ND
2014-06-16	9590-008-0831	14.0 ppb
2014-06-17	9590-018-0817	ND
2014-06-17	9590-030-0756	2.80 ppb
2014-06-17	9590-034-0733	ND
2014-06-19	9590-008-1105	8.40 ppb
2014-07-23	9590-900-1339	7.60 ppb
2014-07-23	9590-901-1121	19.0 ppb
2014-07-23	9590-902-1101	20.0 ppb
2014-07-23	9590-903-1237	8.50 ppb
2014-07-23	9590-904-1306	11.0 ppb
2014-07-23	9590-905-1145	9.20 ppb
2014-07-23	9590-906-1216	9.30 ppb
2014-07-23	9590-907-1430	13.0 ppb
2014-08-06	9590-008-1044	5.10 ppb
2014-09-04	9590-004-0737	ND
2014-10-01	9590-032-0746	1.80 ppb
2014-10-28	9590-900-1354	8.80 ppb
2014-10-28	9590-901-1257	17.0 ppb
2014-10-28	9590-902-1238	24.0 ppb
2014-10-28	9590-903-1433	12.0 ppb
2014-10-28	9590-904-1451	12.0 ppb
2014-10-28	9590-905-1509	21.0 ppb
2014-10-28	9590-906-1416	11.0 ppb
2014-10-28	9590-907-1320	9.00 ppb
2014-10-30	9590-008-1325	3.00 ppb
2015-01-21	9590-900-1058	24.0 ppb
2015-01-21	9590-901-0910	25.0 ppb
2015-01-21	9590-902-0850	24.0 ppb
2015-01-21	9590-903-1132	25.0 ppb
2015-01-21	9590-904-1222	18.0 ppb
2015-01-21	9590-905-1151	27.0 ppb
2015-01-21	9590-906-0937	23.0 ppb
2015-01-21	9590-907-0959	18.0 ppb
2015-04-21	9590-900-1325	37.0 ppb
2015-04-21	9590-901-0804	23.0 ppb
2015-04-21	9590-902-1215	26.0 ppb
2015-04-21	9590-903-1024	26.0 ppb
2015-04-21	9590-904-1142	16.0 ppb
2015-04-21	9590-905-1111	31.0 ppb
2015-04-21	9590-906-0912	28.0 ppb
2015-04-21	9590-907-0848	30.0 ppb
2015-06-10	9590-008-1040	7.10 ppb
2015-07-16	9590-900-0856	14.0 ppb
2015-07-16	9590-901-0747	11.0 ppb
2015-07-16	9590-902-0728	26.0 ppb
2015-07-16	9590-903-0941	26.0 ppb
2015-07-16	9590-904-1002	13.0 ppb
2015-07-16	9590-905-1026	27.0 ppb
2015-07-16	9590-906-0923	17.0 ppb
2015-07-16	9590-907-0816	9.30 ppb
2015-08-24	9590-008-1222	ND
2015-10-08	9590-900-1027	2.30 ppb
2015-10-08	9590-901-0930	8.90 ppb
2015-10-08	9590-902-0906	40.0 ppb
2015-10-08	9590-903-1243	41.0 ppb
2015-10-08	9590-904-1302	38.0 ppb
2015-10-08	9590-905-1321	29.0 ppb
2015-10-08	9590-906-1050	2.60 ppb
2015-10-08	9590-907-0951	ND
2016-01-27	9590-900-1109	36.0 ppb
2016-01-27	9590-901-0830	32.0 ppb
2016-01-27	9590-902-0806	28.0 ppb
2016-01-27	9590-903-0941	40.0 ppb
2016-01-27	9590-904-1027	22.0 ppb
2016-01-27	9590-905-1001	28.0 ppb
2016-01-27	9590-906-0919	27.0 ppb
2016-01-27	9590-907-0853	21.0 ppb
2016-04-20	9590-900-1110	20.0 ppb
2016-04-20	9590-901-0954	33.0 ppb
2016-04-20	9590-902-1307	59.0 ppb
2016-04-20	9590-903-1202	65.0 ppb
2016-04-20	9590-904-1240	51.0 ppb
2016-04-20	9590-905-1221	64.0 ppb
2016-04-20	9590-906-1041	40.0 ppb
2016-04-20	9590-907-1020	14.0 ppb
2016-06-29	9590-018-0750	ND
2016-06-29	9590-032-0820	ND
2016-07-11	9590-900-0920	25.0 ppb
2016-07-11	9590-901-0818	22.0 ppb
2016-07-11	9590-902-1140	39.0 ppb
2016-07-11	9590-903-1034	38.0 ppb
2016-07-11	9590-904-1112	30.0 ppb
2016-07-11	9590-905-1050	37.0 ppb
2016-07-11	9590-906-1012	30.0 ppb
2016-07-11	9590-907-0947	12.0 ppb
2016-07-20	9590-008-1000	16.0 ppb
2016-08-04	9590-003-0706	ND
2016-08-04	9590-004-0651	ND
2016-08-04	9590-006-0725	ND
2016-09-14	9590-034-0812	ND
2016-09-22	9590-005-0825	ND
2016-10-05	9590-900-1024	39.0 ppb
2016-10-05	9590-901-0830	25.0 ppb
2016-10-05	9590-902-0750	42.0 ppb
2016-10-05	9590-903-1049	42.0 ppb
2016-10-05	9590-904-1107	42.0 ppb
2016-10-05	9590-905-1125	42.0 ppb
2016-10-05	9590-906-0900	37.0 ppb
2016-10-05	9590-907-0948	24.0 ppb
2017-01-05	9590-900-0845	54.0 ppb
2017-01-05	9590-901-0939	39.0 ppb
2017-01-05	9590-902-0922	36.0 ppb
2017-01-05	9590-903-1039	45.0 ppb
2017-01-05	9590-904-1112	36.0 ppb
2017-01-05	9590-905-1053	35.0 ppb
2017-01-05	9590-906-1024	35.0 ppb
2017-01-05	9590-907-1000	35.0 ppb
2017-03-08	9590-030-1230	ND
2017-04-04	9590-900-0935	96.0 ppb
2017-04-04	9590-901-0853	88.0 ppb
2017-04-04	9590-902-1256	73.0 ppb
2017-04-04	9590-903-1145	94.0 ppb
2017-04-04	9590-904-1205	72.0 ppb
2017-04-04	9590-905-1232	70.0 ppb
2017-04-04	9590-906-1128	67.0 ppb
2017-04-04	9590-907-1111	52.0 ppb
2017-06-28	9590-008-1158	ND
2017-06-28	9590-018-0714	ND
2017-06-28	9590-032-0814	ND
2017-06-28	9590-034-0742	ND
2017-07-10	9590-900-0952	1.60 ppb
2017-07-10	9590-901-0914	20.0 ppb
2017-07-10	9590-902-0850	58.0 ppb
2017-07-10	9590-903-1109	60.0 ppb
2017-07-10	9590-904-1128	60.0 ppb
2017-07-10	9590-905-1224	59.0 ppb
2017-07-10	9590-906-1052	1.50 ppb
2017-07-10	9590-907-1032	3.50 ppb
2017-08-16	9590-900-1122	22.0 ppb
2017-08-16	9590-901-1242	22.0 ppb
2017-08-16	9590-906-1211	25.0 ppb
2017-08-16	9590-907-1151	2.20 ppb
2017-09-14	9590-003-0749	ND
2017-09-14	9590-004-0738	ND
2017-09-14	9590-005-0814	ND
2017-09-14	9590-006-0824	1.60 ppb
2017-10-09	9590-900-1117	3.00 ppb
2017-10-09	9590-901-1159	39.0 ppb
2017-10-09	9590-902-0811	42.0 ppb
2017-10-09	9590-903-0939	29.0 ppb
2017-10-09	9590-904-0858	44.0 ppb
2017-10-09	9590-905-0839	44.0 ppb
2017-10-09	9590-906-1002	15.0 ppb
2017-10-09	9590-907-1018	4.20 ppb
2018-01-22	9590-901-0933	44.0 ppb
2018-01-22	9590-902-0910	32.0 ppb
2018-01-22	9590-903-1216	45.0 ppb
2018-01-22	9590-904-1142	36.0 ppb
2018-01-22	9590-905-1232	36.0 ppb
2018-01-22	9590-906-1022	36.0 ppb
2018-01-22	9590-907-1000	28.0 ppb
2018-01-30	9590-900-1055	68.0 ppb
2018-04-02	9590-900-0958	46.0 ppb
2018-04-02	9590-901-0842	32.0 ppb
2018-04-02	9590-902-0818	27.0 ppb
2018-04-02	9590-903-1033	49.0 ppb
2018-04-02	9590-904-1114	34.0 ppb
2018-04-02	9590-905-1150	31.0 ppb
2018-04-02	9590-906-0923	30.0 ppb
2018-04-02	9590-907-0903	27.0 ppb
2018-06-06	9590-018-0657	ND
2018-06-06	9590-032-0750	ND
2018-06-07	9590-003-0753	ND
2018-06-07	9590-004-0741	ND
2018-06-13	9590-034-0856	9.40 ppb
2018-06-21	9590-034-0747	ND
2018-07-09	9590-900-0832	4.40 ppb
2018-07-09	9590-901-1018	6.10 ppb
2018-07-09	9590-902-0951	33.0 ppb
2018-07-09	9590-903-1004	15.0 ppb
2018-07-09	9590-904-1048	29.0 ppb
2018-07-09	9590-905-1124	24.0 ppb
2018-07-09	9590-906-0916	13.0 ppb
2018-07-09	9590-907-0856	9.90 ppb
2018-07-11	9590-005-0825	ND
2018-07-11	9590-006-0758	ND
2018-07-11	9590-008-0832	ND
2018-10-10	9590-900-1020	3.50 ppb
2018-10-10	9590-901-0832	9.80 ppb
2018-10-10	9590-902-0817	42.0 ppb
2018-10-10	9590-903-1144	4.90 ppb
2018-10-10	9590-904-1125	22.0 ppb
2018-10-10	9590-905-1158	39.0 ppb
2018-10-10	9590-906-0952	1.10 ppb
2018-10-10	9590-907-0920	9.70 ppb
2019-01-10	9590-900-1027	4.60 ppb
2019-01-10	9590-901-0856	8.50 ppb
2019-01-10	9590-902-0837	30.0 ppb
2019-01-10	9590-903-1209	11.0 ppb
2019-01-10	9590-904-1130	20.0 ppb
2019-01-10	9590-905-1222	27.0 ppb
2019-01-10	9590-906-0957	3.80 ppb
2019-01-10	9590-907-0929	5.20 ppb
2019-04-01	9590-900-1019	59.0 ppb
2019-04-01	9590-901-0857	ND
2019-04-01	9590-902-0839	40.0 ppb
2019-04-01	9590-903-0840	42.0 ppb
2019-04-01	9590-904-1046	32.0 ppb
2019-04-01	9590-905-0856	46.0 ppb
2019-04-01	9590-906-0946	48.0 ppb
2019-04-01	9590-907-0926	28.0 ppb
2019-06-04	9590-008-1025	ND
2019-07-08	9590-900-0940	15.0 ppb
2019-07-08	9590-901-0801	15.0 ppb
2019-07-08	9590-902-0742	38.0 ppb
2019-07-08	9590-903-1028	6.20 ppb
2019-07-08	9590-904-1010	26.0 ppb
2019-07-08	9590-905-1044	29.0 ppb
2019-07-08	9590-906-0846	8.20 ppb
2019-07-08	9590-907-0825	10.00 ppb
2019-10-10	9590-901-1202	26.0 ppb
2019-10-10	9590-902-1136	43.0 ppb
2019-10-10	9590-907-1232	18.0 ppb
2019-10-14	9590-900-0835	19.0 ppb
2019-10-14	9590-903-0943	36.0 ppb
2019-10-14	9590-904-0911	29.0 ppb
2019-10-14	9590-905-1008	47.0 ppb
2019-10-14	9590-906-1258	27.0 ppb