Chloroform
Marin Municipal Water 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.
Testing results - average by year
Year | Average result | Samples taken | Detections | Range of results |
---|---|---|---|---|
2013 | N/A | 0 | 0 | N/A |
2014 | 16.4 ppb | 40 | 40 | 2.50 ppb - 51.0 ppb |
2015 | 22.3 ppb | 43 | 43 | 3.10 ppb - 63.6 ppb |
2016 | 18.9 ppb | 42 | 42 | 6.10 ppb - 63.5 ppb |
2017 | 9.65 ppb | 41 | 41 | 3.30 ppb - 23.3 ppb |
2018 | 13.3 ppb | 41 | 41 | 3.10 ppb - 38.9 ppb |
2019 | 14.2 ppb | 35 | 35 | 4.40 ppb - 68.4 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 |
---|---|---|
2014-02-10 | 7747-004-1205 | 18.2 ppb |
2014-02-10 | 7747-005-0740 | 2.90 ppb |
2014-02-10 | 7747-011-1110 | 8.00 ppb |
2014-02-10 | 7747-016-1145 | 3.90 ppb |
2014-02-10 | 7747-025-1050 | 12.6 ppb |
2014-02-10 | 7747-028-0945 | 13.1 ppb |
2014-02-10 | 7747-029-0945 | 10.00 ppb |
2014-02-10 | 7747-030-1255 | 5.50 ppb |
2014-02-10 | 7747-032-0820 | 10.00 ppb |
2014-02-10 | 7747-034-0840 | 3.30 ppb |
2014-05-05 | 9590-005-1200 | 6.80 ppb |
2014-05-12 | 7747-004-1420 | 12.1 ppb |
2014-05-12 | 7747-005-0755 | 4.80 ppb |
2014-05-12 | 7747-011-1145 | 7.40 ppb |
2014-05-12 | 7747-016-1420 | 6.50 ppb |
2014-05-12 | 7747-025-0800 | 15.6 ppb |
2014-05-12 | 7747-028-1000 | 17.7 ppb |
2014-05-12 | 7747-029-1105 | 7.60 ppb |
2014-05-12 | 7747-030-0855 | 8.20 ppb |
2014-05-12 | 7747-032-0950 | 7.50 ppb |
2014-05-12 | 7747-034-0955 | 5.70 ppb |
2014-08-11 | 1610-004-1050 | 41.2 ppb |
2014-08-11 | 1610-011-0915 | 30.6 ppb |
2014-08-11 | 1610-016-0835 | 25.2 ppb |
2014-08-11 | 1610-025-1150 | 42.1 ppb |
2014-08-11 | 1610-028-1015 | 42.4 ppb |
2014-08-11 | 1610-030-1220 | 31.6 ppb |
2014-08-11 | 1610-032-1150 | 25.6 ppb |
2014-08-11 | 1610-034-1000 | 30.3 ppb |
2014-08-11 | 1610-034-1340 | 23.4 ppb |
2014-11-10 | 7747-004-1210 | 35.7 ppb |
2014-11-10 | 7747-005-0820 | 2.50 ppb |
2014-11-10 | 7747-011-1125 | 7.60 ppb |
2014-11-10 | 7747-016-1155 | 8.50 ppb |
2014-11-10 | 7747-025-1010 | 35.8 ppb |
2014-11-10 | 7747-028-1100 | 51.0 ppb |
2014-11-10 | 7747-029-1045 | 12.5 ppb |
2014-11-10 | 7747-030-1305 | 7.90 ppb |
2014-11-10 | 7747-032-0950 | 13.3 ppb |
2014-11-10 | 7747-034-0915 | 3.40 ppb |
2015-02-09 | 7747-004-1350 | 22.7 ppb |
2015-02-09 | 7747-005-0750 | 7.50 ppb |
2015-02-09 | 7747-011-1225 | 12.1 ppb |
2015-02-09 | 7747-016-1405 | 19.1 ppb |
2015-02-09 | 7747-025-0745 | 22.7 ppb |
2015-02-09 | 7747-028-0910 | 49.9 ppb |
2015-02-09 | 7747-029-1135 | 12.5 ppb |
2015-02-09 | 7747-030-0920 | 12.5 ppb |
2015-02-09 | 7747-032-1015 | 8.90 ppb |
2015-02-09 | 7747-034-1055 | 8.50 ppb |
2015-05-04 | 1644-005-0815 | 3.10 ppb |
2015-05-11 | 7747-004-0850 | 41.1 ppb |
2015-05-11 | 7747-005-0800 | 3.90 ppb |
2015-05-11 | 7747-011-1135 | 63.6 ppb |
2015-05-11 | 7747-016-1350 | 11.9 ppb |
2015-05-11 | 7747-025-0800 | 41.2 ppb |
2015-05-11 | 7747-028-0950 | 39.9 ppb |
2015-05-11 | 7747-029-1040 | 61.0 ppb |
2015-05-11 | 7747-030-1315 | 28.6 ppb |
2015-05-11 | 7747-032-1310 | 53.8 ppb |
2015-05-11 | 7747-034-1035 | 4.30 ppb |
2015-05-26 | 7747-004-0820 | 29.8 ppb |
2015-05-26 | 7747-011-1025 | 37.2 ppb |
2015-08-10 | 7747-004-1015 | 24.5 ppb |
2015-08-10 | 7747-005-0650 | 3.60 ppb |
2015-08-10 | 7747-011-1305 | 8.80 ppb |
2015-08-10 | 7747-016-0900 | 24.2 ppb |
2015-08-10 | 7747-025-1035 | 27.3 ppb |
2015-08-10 | 7747-028-1145 | 24.3 ppb |
2015-08-10 | 7747-029-1200 | 19.8 ppb |
2015-08-10 | 7747-030-0820 | 9.00 ppb |
2015-08-10 | 7747-032-0900 | 27.5 ppb |
2015-08-10 | 7747-034-0845 | 3.40 ppb |
2015-11-10 | 7747-004-1050 | 20.1 ppb |
2015-11-10 | 7747-005-1230 | 4.20 ppb |
2015-11-10 | 7747-011-0920 | 24.5 ppb |
2015-11-10 | 7747-016-1443 | 22.8 ppb |
2015-11-10 | 7747-025-0845 | 21.2 ppb |
2015-11-10 | 7747-028-0930 | 20.5 ppb |
2015-11-10 | 7747-029-1015 | 27.4 ppb |
2015-11-10 | 7747-030-0835 | 22.8 ppb |
2015-11-10 | 7747-032-1145 | 21.8 ppb |
2015-11-10 | 7747-034-1130 | 4.20 ppb |
2016-02-10 | 7747-004-0950 | 14.4 ppb |
2016-02-10 | 7747-005-1015 | 19.2 ppb |
2016-02-10 | 7747-011-1140 | 12.7 ppb |
2016-02-10 | 7747-016-0920 | 12.6 ppb |
2016-02-10 | 7747-025-0830 | 15.1 ppb |
2016-02-10 | 7747-028-0750 | 25.7 ppb |
2016-02-10 | 7747-029-1050 | 13.6 ppb |
2016-02-10 | 7747-030-0750 | 14.0 ppb |
2016-02-10 | 7747-032-0845 | 12.8 ppb |
2016-02-10 | 7747-034-1100 | 19.0 ppb |
2016-05-09 | 7747-004-1310 | 20.0 ppb |
2016-05-09 | 7747-005-0910 | 6.50 ppb |
2016-05-09 | 7747-011-1055 | 31.6 ppb |
2016-05-09 | 7747-016-0835 | 9.60 ppb |
2016-05-09 | 7747-025-0730 | 19.7 ppb |
2016-05-09 | 7747-028-0835 | 19.2 ppb |
2016-05-09 | 7747-029-1015 | 30.9 ppb |
2016-05-09 | 7747-030-0820 | 26.1 ppb |
2016-05-09 | 7747-032-0915 | 25.0 ppb |
2016-05-09 | 7747-034-1010 | 6.10 ppb |
2016-05-16 | 7747-011-0001 | 63.5 ppb |
2016-05-20 | 7747-004-0930 | 48.8 ppb |
2016-08-08 | 7747-004-1335 | 22.4 ppb |
2016-08-08 | 7747-005-0720 | 6.70 ppb |
2016-08-08 | 7747-011-1155 | 7.00 ppb |
2016-08-08 | 7747-016-1250 | 15.6 ppb |
2016-08-08 | 7747-025-1155 | 22.7 ppb |
2016-08-08 | 7747-028-1125 | 22.4 ppb |
2016-08-08 | 7747-029-1120 | 7.60 ppb |
2016-08-08 | 7747-030-1015 | 7.70 ppb |
2016-08-08 | 7747-032-1035 | 9.80 ppb |
2016-08-08 | 7747-034-0925 | 7.10 ppb |
2016-11-14 | 7747-004-0950 | 19.6 ppb |
2016-11-14 | 7747-005-0745 | 9.30 ppb |
2016-11-14 | 7747-011-1105 | 24.4 ppb |
2016-11-14 | 7747-016-1400 | 25.9 ppb |
2016-11-14 | 7747-025-0800 | 20.3 ppb |
2016-11-14 | 7747-028-0920 | 18.2 ppb |
2016-11-14 | 7747-029-1230 | 26.2 ppb |
2016-11-14 | 7747-030-1335 | 23.5 ppb |
2016-11-14 | 7747-032-1315 | 20.7 ppb |
2016-11-14 | 7747-034-0945 | 10.3 ppb |
2017-02-13 | 7747-004-1200 | 10.8 ppb |
2017-02-13 | 7747-005-1005 | 11.3 ppb |
2017-02-13 | 7747-011-0950 | 7.70 ppb |
2017-02-13 | 7747-016-0915 | 9.20 ppb |
2017-02-13 | 7747-025-0745 | 10.9 ppb |
2017-02-13 | 7747-028-0825 | 13.2 ppb |
2017-02-13 | 7747-029-0905 | 8.80 ppb |
2017-02-13 | 7747-030-0800 | 8.40 ppb |
2017-02-13 | 7747-032-1310 | 8.40 ppb |
2017-02-13 | 7747-034-1150 | 13.9 ppb |
2017-05-01 | 9590-005-0800 | 9.60 ppb |
2017-05-08 | 1610-004-1050 | 12.5 ppb |
2017-05-08 | 1610-005-0720 | 5.36 ppb |
2017-05-08 | 1610-011-1225 | 6.15 ppb |
2017-05-08 | 1610-016-1255 | 5.85 ppb |
2017-05-08 | 1610-025-1355 | 8.47 ppb |
2017-05-08 | 1610-028-1330 | 6.84 ppb |
2017-05-08 | 1610-029-1140 | 6.39 ppb |
2017-05-08 | 1610-030-0900 | 6.39 ppb |
2017-05-08 | 1610-032-0935 | 5.51 ppb |
2017-05-08 | 1610-034-0900 | 3.45 ppb |
2017-08-14 | 7747-004-1220 | 11.9 ppb |
2017-08-14 | 7747-005-0800 | 3.30 ppb |
2017-08-14 | 7747-011-1100 | 7.20 ppb |
2017-08-14 | 7747-016-1420 | 7.20 ppb |
2017-08-14 | 7747-025-1115 | 15.1 ppb |
2017-08-14 | 7747-028-1215 | 11.9 ppb |
2017-08-14 | 7747-029-1015 | 7.10 ppb |
2017-08-14 | 7747-030-0900 | 6.70 ppb |
2017-08-14 | 7747-032-0920 | 6.50 ppb |
2017-08-14 | 7747-034-0740 | 3.80 ppb |
2017-11-13 | 7747-004-1100 | 12.6 ppb |
2017-11-13 | 7747-005-0720 | 6.10 ppb |
2017-11-13 | 7747-011-1100 | 16.2 ppb |
2017-11-13 | 7747-016-1340 | 9.90 ppb |
2017-11-13 | 7747-025-0800 | 12.2 ppb |
2017-11-13 | 7747-028-0930 | 23.3 ppb |
2017-11-13 | 7747-029-1150 | 17.0 ppb |
2017-11-13 | 7747-030-0850 | 16.3 ppb |
2017-11-13 | 7747-032-0815 | 16.1 ppb |
2017-11-13 | 7747-034-0930 | 6.10 ppb |
2018-02-12 | 7747-004-1020 | 13.2 ppb |
2018-02-12 | 7747-005-0700 | 9.40 ppb |
2018-02-12 | 7747-011-1210 | 13.0 ppb |
2018-02-12 | 7747-016-1340 | 21.3 ppb |
2018-02-12 | 7747-025-0915 | 13.0 ppb |
2018-02-12 | 7747-028-1050 | 11.0 ppb |
2018-02-12 | 7747-029-1130 | 14.0 ppb |
2018-02-12 | 7747-030-0800 | 14.0 ppb |
2018-02-12 | 7747-032-0900 | 12.9 ppb |
2018-02-12 | 7747-034-0935 | 9.50 ppb |
2018-05-07 | 9590-005-0800 | 6.70 ppb |
2018-05-14 | 7747-004-1115 | 18.0 ppb |
2018-05-14 | 7747-005-0730 | 5.00 ppb |
2018-05-14 | 7747-011-1020 | 18.0 ppb |
2018-05-14 | 7747-016-1355 | 12.0 ppb |
2018-05-14 | 7747-025-1045 | 19.0 ppb |
2018-05-14 | 7747-028-0935 | 16.5 ppb |
2018-05-14 | 7747-029-0940 | 18.0 ppb |
2018-05-14 | 7747-030-0900 | 19.2 ppb |
2018-05-14 | 7747-032-1300 | 17.3 ppb |
2018-05-14 | 7747-034-0815 | 6.70 ppb |
2018-08-13 | 7747-004-1045 | 19.3 ppb |
2018-08-13 | 7747-005-0830 | 3.40 ppb |
2018-08-13 | 7747-011-1310 | 14.4 ppb |
2018-08-13 | 7747-016-1350 | 15.4 ppb |
2018-08-13 | 7747-025-0915 | 19.2 ppb |
2018-08-13 | 7747-028-1030 | 38.9 ppb |
2018-08-13 | 7747-029-1215 | 14.5 ppb |
2018-08-13 | 7747-030-0900 | 15.2 ppb |
2018-08-13 | 7747-032-0930 | 10.00 ppb |
2018-08-13 | 7747-034-1000 | 3.10 ppb |
2018-11-13 | 7747-004-1000 | 16.2 ppb |
2018-11-13 | 7747-005-0730 | 3.90 ppb |
2018-11-13 | 7747-011-1200 | 7.80 ppb |
2018-11-13 | 7747-016-1100 | 12.3 ppb |
2018-11-13 | 7747-025-0730 | 14.8 ppb |
2018-11-13 | 7747-028-0850 | 20.4 ppb |
2018-11-13 | 7747-029-1245 | 7.50 ppb |
2018-11-13 | 7747-030-0920 | 7.90 ppb |
2018-11-13 | 7747-032-1015 | 9.10 ppb |
2018-11-13 | 7747-034-1145 | 5.30 ppb |
2019-02-19 | 1644-004-1025 | 9.60 ppb |
2019-02-19 | 1644-016-1320 | 8.40 ppb |
2019-02-19 | 1644-025-0750 | 10.00 ppb |
2019-02-19 | 1644-028-1000 | 38.0 ppb |
2019-02-19 | 1644-029-0800 | 7.60 ppb |
2019-02-19 | 1644-030-0955 | 7.20 ppb |
2019-02-19 | 1644-032-0915 | 6.30 ppb |
2019-02-19 | 1644-034-0945 | 14.0 ppb |
2019-05-06 | 1644-005-0730 | 4.40 ppb |
2019-05-16 | 7747-004-1250 | 15.6 ppb |
2019-05-16 | 7747-005-0710 | 7.30 ppb |
2019-05-16 | 7747-011-1135 | 9.50 ppb |
2019-05-16 | 7747-016-1025 | 7.60 ppb |
2019-05-16 | 7747-025-1235 | 11.6 ppb |
2019-05-16 | 7747-028-1115 | 12.5 ppb |
2019-05-16 | 7747-029-1045 | 9.10 ppb |
2019-05-16 | 7747-030-0930 | 10.4 ppb |
2019-05-16 | 7747-032-0955 | 9.50 ppb |
2019-05-16 | 7747-034-0835 | 5.70 ppb |
2019-08-12 | 7747-004-1245 | 18.1 ppb |
2019-08-12 | 7747-016-1340 | 31.1 ppb |
2019-08-12 | 7747-025-1150 | 18.9 ppb |
2019-08-12 | 7747-028-1240 | 68.4 ppb |
2019-08-12 | 7747-029-0820 | 21.1 ppb |
2019-08-12 | 7747-030-0740 | 21.8 ppb |
2019-08-12 | 7747-032-1315 | 23.5 ppb |
2019-08-12 | 7747-034-1115 | 4.50 ppb |
2019-11-12 | 7747-004-1145 | 11.0 ppb |
2019-11-12 | 7747-016-1410 | 7.80 ppb |
2019-11-12 | 7747-025-0950 | 13.7 ppb |
2019-11-12 | 7747-028-1105 | 23.5 ppb |
2019-11-12 | 7747-029-0825 | 7.00 ppb |
2019-11-12 | 7747-030-0925 | 6.80 ppb |
2019-11-12 | 7747-032-1315 | 7.30 ppb |
2019-11-12 | 7747-034-0915 | 6.60 ppb |