Chloroform
City of Napa
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 | 39.4 ppb | 39 | 38 | ND - 120.0 ppb |
2015 | 44.2 ppb | 44 | 44 | 4.10 ppb - 100.0 ppb |
2016 | 31.8 ppb | 37 | 37 | 11.0 ppb - 60.0 ppb |
2017 | 29.5 ppb | 44 | 44 | 11.0 ppb - 68.0 ppb |
2018 | 29.6 ppb | 45 | 45 | 6.70 ppb - 50.0 ppb |
2019 | 29.6 ppb | 48 | 48 | 5.10 ppb - 51.0 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 |
---|---|---|
2014-01-08 | 1233-007-0935 | 5.60 ppb |
2014-01-08 | 1233-008-1030 | 17.0 ppb |
2014-01-08 | 1233-009-1000 | 13.0 ppb |
2014-01-08 | 1233-010-1050 | 13.0 ppb |
2014-01-08 | 1233-011-1245 | 20.0 ppb |
2014-01-08 | 1233-012-1305 | 15.0 ppb |
2014-01-08 | 1233-024-1230 | 14.0 ppb |
2014-01-08 | 1233-025-1110 | 16.0 ppb |
2014-01-08 | 1233-028-1315 | 18.0 ppb |
2014-04-02 | 1233-006-1245 | 42.0 ppb |
2014-04-02 | 1233-008-1055 | 82.0 ppb |
2014-04-02 | 1233-009-1040 | 54.0 ppb |
2014-04-02 | 1233-010-1110 | 59.0 ppb |
2014-04-02 | 1233-011-1330 | 56.0 ppb |
2014-04-02 | 1233-012-1355 | 74.0 ppb |
2014-04-02 | 1233-024-1315 | 42.0 ppb |
2014-04-02 | 1233-025-1130 | 85.0 ppb |
2014-04-02 | 1233-028-1345 | 72.0 ppb |
2014-07-09 | 1233-005-1145 | 8.60 ppb |
2014-07-09 | 1233-006-1245 | 39.0 ppb |
2014-07-09 | 1233-007-0925 | 9.80 ppb |
2014-07-09 | 1233-008-1030 | 45.0 ppb |
2014-07-09 | 1233-009-1015 | 43.0 ppb |
2014-07-09 | 1233-010-1040 | 25.0 ppb |
2014-07-09 | 1233-011-1410 | 33.0 ppb |
2014-07-09 | 1233-012-1440 | 28.0 ppb |
2014-07-09 | 1233-024-1355 | 120.0 ppb |
2014-07-09 | 1233-025-1105 | 33.0 ppb |
2014-07-09 | 1233-028-1430 | 48.0 ppb |
2014-10-01 | 1233-006-1220 | 65.0 ppb |
2014-10-01 | 1233-007-1010 | 13.0 ppb |
2014-10-01 | 1233-008-1050 | 41.0 ppb |
2014-10-01 | 1233-009-1035 | 35.0 ppb |
2014-10-01 | 1233-010-1105 | 27.0 ppb |
2014-10-01 | 1233-011-1320 | 45.0 ppb |
2014-10-01 | 1233-012-1355 | 34.0 ppb |
2014-10-01 | 1233-024-1300 | ND |
2014-10-01 | 1233-025-1125 | 45.0 ppb |
2014-10-01 | 1233-028-1335 | 100.0 ppb |
2015-01-08 | 1233-007-1000 | 39.0 ppb |
2015-01-08 | 1233-008-1105 | 75.0 ppb |
2015-01-08 | 1233-009-1050 | 64.0 ppb |
2015-01-08 | 1233-010-1115 | 66.0 ppb |
2015-01-08 | 1233-011-1215 | 77.0 ppb |
2015-01-08 | 1233-012-1330 | 73.0 ppb |
2015-01-08 | 1233-024-1155 | 79.0 ppb |
2015-01-08 | 1233-025-1130 | 71.0 ppb |
2015-01-08 | 1233-031-1320 | 67.0 ppb |
2015-04-01 | 1233-007-0950 | 23.0 ppb |
2015-04-01 | 1233-008-1045 | 41.0 ppb |
2015-04-01 | 1233-009-1030 | 38.0 ppb |
2015-04-01 | 1233-010-1055 | 31.0 ppb |
2015-04-01 | 1233-011-1330 | 42.0 ppb |
2015-04-01 | 1233-012-1355 | 39.0 ppb |
2015-04-01 | 1233-024-1315 | 52.0 ppb |
2015-04-01 | 1233-025-1115 | 42.0 ppb |
2015-04-01 | 1233-028-1340 | 40.0 ppb |
2015-07-21 | 1233-005-1120 | 9.00 ppb |
2015-07-21 | 1233-006-1415 | 100.0 ppb |
2015-07-21 | 1233-007-0940 | 11.0 ppb |
2015-07-21 | 1233-008-1035 | 49.0 ppb |
2015-07-21 | 1233-009-1020 | 37.0 ppb |
2015-07-21 | 1233-010-1045 | 39.0 ppb |
2015-07-21 | 1233-011-1505 | 47.0 ppb |
2015-07-21 | 1233-012-1530 | 45.0 ppb |
2015-07-21 | 1233-024-1450 | 57.0 ppb |
2015-07-21 | 1233-025-1200 | 42.0 ppb |
2015-07-21 | 1233-028-1520 | 41.0 ppb |
2015-10-07 | 1233-005-1155 | 15.0 ppb |
2015-10-07 | 1233-006-1325 | 27.0 ppb |
2015-10-07 | 1233-007-1110 | 16.0 ppb |
2015-10-07 | 1233-008-1510 | 53.0 ppb |
2015-10-07 | 1233-009-1525 | 44.0 ppb |
2015-10-07 | 1233-010-1455 | 31.0 ppb |
2015-10-07 | 1233-011-1415 | 52.0 ppb |
2015-10-07 | 1233-012-1440 | 47.0 ppb |
2015-10-07 | 1233-024-1400 | 56.0 ppb |
2015-10-07 | 1233-025-1210 | 51.0 ppb |
2015-10-07 | 1233-028-1430 | 32.0 ppb |
2015-11-04 | 1233-006-1220 | 37.0 ppb |
2015-11-04 | 1233-007-1030 | 6.20 ppb |
2015-12-02 | 1233-006-1145 | 38.0 ppb |
2015-12-02 | 1233-007-1030 | 4.10 ppb |
2016-01-08 | 1233-008-1245 | 23.0 ppb |
2016-01-08 | 1233-009-1230 | 12.0 ppb |
2016-01-08 | 1233-010-1300 | 11.0 ppb |
2016-01-08 | 1233-011-1355 | 24.0 ppb |
2016-01-08 | 1233-012-1430 | 26.0 ppb |
2016-01-08 | 1233-024-1340 | 30.0 ppb |
2016-01-08 | 1233-025-1320 | 24.0 ppb |
2016-01-08 | 1233-028-1415 | 20.0 ppb |
2016-04-06 | 1233-006-1230 | 17.0 ppb |
2016-04-06 | 1233-008-1100 | 38.0 ppb |
2016-04-06 | 1233-009-1045 | 34.0 ppb |
2016-04-06 | 1233-010-1115 | 36.0 ppb |
2016-04-06 | 1233-011-1345 | 28.0 ppb |
2016-04-06 | 1233-024-1330 | 23.0 ppb |
2016-04-06 | 1233-025-1130 | 42.0 ppb |
2016-04-06 | 1233-028-1400 | 30.0 ppb |
2016-05-04 | 1233-007-1025 | 35.0 ppb |
2016-07-27 | 1233-006-1545 | 21.0 ppb |
2016-07-27 | 1233-007-1245 | 19.0 ppb |
2016-07-27 | 1233-008-1320 | 60.0 ppb |
2016-07-27 | 1233-009-1305 | 36.0 ppb |
2016-07-27 | 1233-010-1335 | 28.0 ppb |
2016-07-27 | 1233-011-1655 | 43.0 ppb |
2016-07-27 | 1233-012-1725 | 40.0 ppb |
2016-07-27 | 1233-024-1645 | 32.0 ppb |
2016-07-27 | 1233-025-1350 | 54.0 ppb |
2016-07-27 | 1233-028-1710 | 37.0 ppb |
2016-10-05 | 1233-006-1110 | 23.0 ppb |
2016-10-05 | 1233-007-0900 | 19.0 ppb |
2016-10-05 | 1233-008-1000 | 58.0 ppb |
2016-10-05 | 1233-009-0945 | 37.0 ppb |
2016-10-05 | 1233-010-1015 | 27.0 ppb |
2016-10-05 | 1233-011-1210 | 34.0 ppb |
2016-10-05 | 1233-012-1230 | 44.0 ppb |
2016-10-05 | 1233-024-1155 | 31.0 ppb |
2016-10-05 | 1233-025-1030 | 43.0 ppb |
2016-10-05 | 1233-028-1225 | 37.0 ppb |
2017-01-11 | 1233-007-1040 | 20.0 ppb |
2017-01-11 | 1233-008-1125 | 60.0 ppb |
2017-01-11 | 1233-009-1115 | 47.0 ppb |
2017-01-11 | 1233-010-1135 | 36.0 ppb |
2017-01-11 | 1233-011-1430 | 43.0 ppb |
2017-01-11 | 1233-012-1500 | 39.0 ppb |
2017-01-11 | 1233-024-1415 | 53.0 ppb |
2017-01-11 | 1233-025-1155 | 49.0 ppb |
2017-01-11 | 1233-028-1445 | 68.0 ppb |
2017-02-01 | 1233-007-1050 | 23.0 ppb |
2017-04-05 | 1233-006-1040 | 15.0 ppb |
2017-04-05 | 1233-008-0912 | 40.0 ppb |
2017-04-05 | 1233-009-0900 | 29.0 ppb |
2017-04-05 | 1233-010-0928 | 30.0 ppb |
2017-04-05 | 1233-011-1153 | 25.0 ppb |
2017-04-05 | 1233-012-1214 | 38.0 ppb |
2017-04-05 | 1233-024-1137 | 20.0 ppb |
2017-04-05 | 1233-025-0950 | 29.0 ppb |
2017-04-05 | 1233-028-1223 | 37.0 ppb |
2017-07-20 | 1233-006-1330 | 19.0 ppb |
2017-07-20 | 1233-007-1050 | 37.0 ppb |
2017-07-20 | 1233-008-1141 | 29.0 ppb |
2017-07-20 | 1233-009-1127 | 33.0 ppb |
2017-07-20 | 1233-010-1155 | 34.0 ppb |
2017-07-20 | 1233-011-1455 | 27.0 ppb |
2017-07-20 | 1233-012-1515 | 26.0 ppb |
2017-07-20 | 1233-024-1436 | 22.0 ppb |
2017-07-20 | 1233-025-1216 | 36.0 ppb |
2017-07-20 | 1233-028-1536 | 26.0 ppb |
2017-09-06 | 1233-006-0955 | 21.0 ppb |
2017-09-06 | 1233-007-0845 | 27.0 ppb |
2017-09-13 | 1233-005-0840 | 18.0 ppb |
2017-10-04 | 1233-005-1154 | 13.0 ppb |
2017-10-04 | 1233-007-0903 | 15.0 ppb |
2017-10-04 | 1233-008-0959 | 18.0 ppb |
2017-10-04 | 1233-009-0943 | 24.0 ppb |
2017-10-04 | 1233-010-1014 | 16.0 ppb |
2017-10-04 | 1233-011-1059 | 23.0 ppb |
2017-10-04 | 1233-012-1034 | 21.0 ppb |
2017-10-04 | 1233-024-1116 | 25.0 ppb |
2017-10-04 | 1233-025-1138 | 20.0 ppb |
2017-10-04 | 1233-028-1046 | 35.0 ppb |
2017-11-01 | 1233-006-1130 | 21.0 ppb |
2017-12-06 | 1233-007-1150 | 11.0 ppb |
2018-01-10 | 1233-007-1230 | 21.0 ppb |
2018-01-10 | 1233-008-1310 | 34.0 ppb |
2018-01-10 | 1233-009-1255 | 32.0 ppb |
2018-01-10 | 1233-010-1325 | 24.0 ppb |
2018-01-10 | 1233-011-1525 | 34.0 ppb |
2018-01-10 | 1233-012-1545 | 33.0 ppb |
2018-01-10 | 1233-024-1515 | 42.0 ppb |
2018-01-10 | 1233-025-1340 | 35.0 ppb |
2018-01-10 | 1233-028-1535 | 23.0 ppb |
2018-04-11 | 1233-006-1430 | 10.00 ppb |
2018-04-11 | 1233-008-1105 | 44.0 ppb |
2018-04-11 | 1233-009-1045 | 32.0 ppb |
2018-04-11 | 1233-010-1125 | 34.0 ppb |
2018-04-11 | 1233-011-1230 | 28.0 ppb |
2018-04-11 | 1233-012-1200 | 42.0 ppb |
2018-04-11 | 1233-024-1245 | 31.0 ppb |
2018-04-11 | 1233-025-1140 | 37.0 ppb |
2018-04-11 | 1233-028-1215 | 45.0 ppb |
2018-06-06 | 1233-006-1240 | 23.0 ppb |
2018-06-06 | 1233-007-1040 | 20.0 ppb |
2018-07-11 | 1233-006-1015 | 25.0 ppb |
2018-07-11 | 1233-007-1200 | 9.40 ppb |
2018-08-08 | 1233-006-1310 | 29.0 ppb |
2018-08-08 | 1233-007-1000 | 15.0 ppb |
2018-09-05 | 1233-006-1045 | 20.0 ppb |
2018-09-05 | 1233-007-1230 | 9.60 ppb |
2018-09-18 | 1233-008-1015 | 43.0 ppb |
2018-09-18 | 1233-009-1000 | 37.0 ppb |
2018-09-18 | 1233-010-1040 | 24.0 ppb |
2018-09-18 | 1233-011-1225 | 30.0 ppb |
2018-09-18 | 1233-012-1300 | 50.0 ppb |
2018-09-18 | 1233-024-1205 | 40.0 ppb |
2018-09-18 | 1233-025-1100 | 33.0 ppb |
2018-09-18 | 1233-028-1245 | 32.0 ppb |
2018-10-03 | 1233-008-1040 | 42.0 ppb |
2018-10-03 | 1233-009-1025 | 32.0 ppb |
2018-10-03 | 1233-010-1055 | 27.0 ppb |
2018-10-03 | 1233-011-1240 | 31.0 ppb |
2018-10-03 | 1233-012-1320 | 23.0 ppb |
2018-10-03 | 1233-024-1220 | 37.0 ppb |
2018-10-03 | 1233-025-1110 | 39.0 ppb |
2018-10-03 | 1233-028-1305 | 29.0 ppb |
2018-11-07 | 1233-006-1225 | 29.0 ppb |
2018-11-07 | 1233-007-1020 | 6.70 ppb |
2018-12-05 | 1233-007-1030 | 16.0 ppb |
2019-01-09 | 1233-007-0940 | 10.00 ppb |
2019-01-09 | 1233-008-1000 | 38.0 ppb |
2019-01-09 | 1233-009-0945 | 34.0 ppb |
2019-01-09 | 1233-010-1010 | 18.0 ppb |
2019-01-09 | 1233-011-1125 | 34.0 ppb |
2019-01-09 | 1233-012-1150 | 36.0 ppb |
2019-01-09 | 1233-024-1105 | 39.0 ppb |
2019-01-09 | 1233-025-1030 | 41.0 ppb |
2019-01-09 | 1233-028-1135 | 40.0 ppb |
2019-03-06 | 1233-006-1020 | 13.0 ppb |
2019-04-03 | 1233-005-1045 | 35.0 ppb |
2019-04-03 | 1233-006-1115 | 16.0 ppb |
2019-04-03 | 1233-009-1015 | 33.0 ppb |
2019-04-03 | 1233-011-1145 | 36.0 ppb |
2019-04-03 | 1233-012-1215 | 43.0 ppb |
2019-04-03 | 1233-024-1130 | 38.0 ppb |
2019-04-03 | 1233-025-1055 | 36.0 ppb |
2019-04-03 | 1233-028-1200 | 29.0 ppb |
2019-05-01 | 1233-006-1040 | 17.0 ppb |
2019-06-12 | 1233-006-1220 | 21.0 ppb |
2019-06-12 | 1233-007-1000 | 13.0 ppb |
2019-07-10 | 1233-006-1200 | 15.0 ppb |
2019-07-10 | 1233-007-0830 | 8.60 ppb |
2019-07-10 | 1233-008-0915 | 49.0 ppb |
2019-07-10 | 1233-009-0900 | 24.0 ppb |
2019-07-10 | 1233-010-0930 | 26.0 ppb |
2019-07-10 | 1233-011-1245 | 30.0 ppb |
2019-07-10 | 1233-012-1315 | 27.0 ppb |
2019-07-10 | 1233-024-1230 | 37.0 ppb |
2019-07-10 | 1233-025-0950 | 40.0 ppb |
2019-07-10 | 1233-028-1300 | 44.0 ppb |
2019-08-07 | 1233-006-1120 | 32.0 ppb |
2019-08-07 | 1233-007-1010 | 20.0 ppb |
2019-09-04 | 1233-006-1050 | 33.0 ppb |
2019-09-04 | 1233-007-0915 | 19.0 ppb |
2019-10-02 | 1233-006-1100 | 25.0 ppb |
2019-10-02 | 1233-007-0840 | 9.40 ppb |
2019-10-02 | 1233-008-0935 | 51.0 ppb |
2019-10-02 | 1233-009-0910 | 34.0 ppb |
2019-10-02 | 1233-010-0950 | 21.0 ppb |
2019-10-02 | 1233-011-1200 | 33.0 ppb |
2019-10-02 | 1233-012-1230 | 32.0 ppb |
2019-10-02 | 1233-024-1140 | 43.0 ppb |
2019-10-02 | 1233-025-1005 | 46.0 ppb |
2019-10-02 | 1233-028-1215 | 42.0 ppb |
2019-11-06 | 1233-006-1045 | 27.0 ppb |
2019-11-06 | 1233-007-0915 | 5.10 ppb |
2019-12-04 | 1233-007-1150 | 28.0 ppb |