Chloroform
San Jose Water Company
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.
Samples
Samples exceeding legal limit (MCL)
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 | 9.58 ppb | 61 | 53 | ND - 68.6 ppb |
2015 | 26.0 ppb | 32 | 30 | ND - 85.4 ppb |
2016 | 13.0 ppb | 49 | 46 | ND - 78.4 ppb |
2017 | 9.04 ppb | 62 | 57 | ND - 37.2 ppb |
2018 | 9.11 ppb | 64 | 59 | ND - 22.1 ppb |
2019 | 11.6 ppb | 64 | 62 | ND - 42.6 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 |
---|---|---|
2014-02-28 | 1610-900-0957 | 3.66 ppb |
2014-02-28 | 1610-901-1241 | 3.50 ppb |
2014-02-28 | 1610-902-0900 | 3.92 ppb |
2014-02-28 | 1610-903-0926 | 3.58 ppb |
2014-02-28 | 1610-904-0910 | 4.91 ppb |
2014-02-28 | 1610-905-1212 | 3.88 ppb |
2014-02-28 | 1610-906-1021 | 4.67 ppb |
2014-02-28 | 1610-907-1225 | 3.73 ppb |
2014-02-28 | 1610-908-0941 | 1.66 ppb |
2014-02-28 | 1610-909-1009 | 3.33 ppb |
2014-02-28 | 1610-910-1032 | 1.25 ppb |
2014-02-28 | 1610-911-1054 | 1.55 ppb |
2014-02-28 | 1610-912-1414 | 2.37 ppb |
2014-02-28 | 1610-913-1351 | 2.83 ppb |
2014-02-28 | 1610-914-1320 | 3.56 ppb |
2014-02-28 | 1610-915-1110 | ND |
2014-05-07 | 1610-900-0925 | 1.02 ppb |
2014-05-07 | 1610-901-1007 | 43.2 ppb |
2014-05-07 | 1610-902-0753 | 4.09 ppb |
2014-05-07 | 1610-903-0913 | 1.47 ppb |
2014-05-07 | 1610-904-0807 | 4.03 ppb |
2014-05-07 | 1610-905-0933 | 67.5 ppb |
2014-05-07 | 1610-906-1035 | ND |
2014-05-07 | 1610-907-0943 | 45.8 ppb |
2014-05-07 | 1610-908-0900 | 1.94 ppb |
2014-05-07 | 1610-909-1025 | 19.5 ppb |
2014-05-07 | 1610-910-1055 | 5.32 ppb |
2014-05-07 | 1610-911-1116 | 1.33 ppb |
2014-05-07 | 1610-912-1323 | 0.870 ppb |
2014-05-07 | 1610-913-1430 | 9.61 ppb |
2014-05-07 | 1610-914-1420 | 7.81 ppb |
2014-05-07 | 1610-915-1235 | ND |
2014-08-25 | 1610-901-1138 | 66.5 ppb |
2014-08-25 | 1610-902-0933 | 3.95 ppb |
2014-08-25 | 1610-904-0947 | 3.46 ppb |
2014-08-25 | 1610-905-1108 | 63.5 ppb |
2014-08-25 | 1610-907-1123 | 60.0 ppb |
2014-08-25 | 1610-908-1025 | 1.17 ppb |
2014-08-25 | 1610-909-1155 | 68.6 ppb |
2014-08-25 | 1610-910-1217 | 5.30 ppb |
2014-08-25 | 1610-911-1333 | 2.75 ppb |
2014-08-25 | 1610-912-1417 | 3.23 ppb |
2014-08-25 | 1610-913-1449 | 8.70 ppb |
2014-08-25 | 1610-914-1438 | 5.83 ppb |
2014-08-25 | 1610-915-1350 | ND |
2014-11-07 | 1610-900-1015 | 1.14 ppb |
2014-11-07 | 1610-901-1055 | 1.68 ppb |
2014-11-07 | 1610-902-0909 | 2.44 ppb |
2014-11-07 | 1610-903-1004 | 1.01 ppb |
2014-11-07 | 1610-904-0920 | 1.74 ppb |
2014-11-07 | 1610-905-1024 | 3.57 ppb |
2014-11-07 | 1610-906-1222 | ND |
2014-11-07 | 1610-907-1040 | 2.06 ppb |
2014-11-07 | 1610-908-0948 | ND |
2014-11-07 | 1610-909-1103 | ND |
2014-11-07 | 1610-910-1243 | 3.57 ppb |
2014-11-07 | 1610-911-1303 | 3.08 ppb |
2014-11-07 | 1610-912-1353 | 3.29 ppb |
2014-11-07 | 1610-913-1427 | 2.94 ppb |
2014-11-07 | 1610-914-1411 | 3.01 ppb |
2014-11-07 | 1610-915-1334 | ND |
2015-02-06 | 1610-900-1014 | 43.7 ppb |
2015-02-06 | 1610-901-0958 | 41.5 ppb |
2015-02-06 | 1610-902-1306 | 1.57 ppb |
2015-02-06 | 1610-903-1228 | 47.4 ppb |
2015-02-06 | 1610-904-1259 | ND |
2015-02-06 | 1610-905-0923 | 61.2 ppb |
2015-02-06 | 1610-906-0858 | 47.1 ppb |
2015-02-06 | 1610-907-0948 | 55.6 ppb |
2015-02-06 | 1610-908-1024 | 3.67 ppb |
2015-02-06 | 1610-909-0913 | 48.2 ppb |
2015-02-06 | 1610-910-1041 | 2.40 ppb |
2015-02-06 | 1610-911-1154 | 2.31 ppb |
2015-02-06 | 1610-912-1339 | 2.98 ppb |
2015-02-06 | 1610-913-1418 | 6.26 ppb |
2015-02-06 | 1610-914-1400 | 8.07 ppb |
2015-02-06 | 1610-915-1051 | ND |
2015-05-29 | 1610-900-1115 | 53.7 ppb |
2015-05-29 | 1610-901-1339 | 57.3 ppb |
2015-05-29 | 1610-902-1000 | 6.01 ppb |
2015-05-29 | 1610-903-1105 | 42.9 ppb |
2015-05-29 | 1610-904-1016 | 6.19 ppb |
2015-05-29 | 1610-905-1310 | 85.4 ppb |
2015-05-29 | 1610-906-1240 | 53.2 ppb |
2015-05-29 | 1610-907-1322 | 62.2 ppb |
2015-05-29 | 1610-908-1050 | 6.20 ppb |
2015-05-29 | 1610-909-1250 | 56.8 ppb |
2015-05-29 | 1610-910-1227 | 4.79 ppb |
2015-05-29 | 1610-911-1403 | 3.29 ppb |
2015-05-29 | 1610-912-1435 | 6.25 ppb |
2015-05-29 | 1610-914-1453 | 6.02 ppb |
2015-05-29 | 1610-915-1216 | 4.80 ppb |
2015-05-29 | 5.31 ppb | |
2016-03-04 | 1610-005-1315 | ND |
2016-04-01 | 1610-005-1140 | ND |
2016-05-06 | 1610-900-0907 | 47.6 ppb |
2016-05-06 | 1610-901-1027 | 44.0 ppb |
2016-05-06 | 1610-902-0800 | 3.89 ppb |
2016-05-06 | 1610-903-0852 | 72.6 ppb |
2016-05-06 | 1610-904-0812 | 5.37 ppb |
2016-05-06 | 1610-905-0945 | 78.4 ppb |
2016-05-06 | 1610-906-1045 | 48.5 ppb |
2016-05-06 | 1610-907-1000 | 61.8 ppb |
2016-05-06 | 1610-908-0835 | 31.1 ppb |
2016-05-06 | 1610-909-0925 | 58.0 ppb |
2016-05-06 | 1610-910-1110 | 4.56 ppb |
2016-05-06 | 1610-911-1145 | 4.27 ppb |
2016-05-06 | 1610-912-1320 | 4.68 ppb |
2016-05-06 | 1610-913-1415 | 18.1 ppb |
2016-05-06 | 1610-914-1350 | 17.3 ppb |
2016-05-06 | 1610-915-1255 | 39.3 ppb |
2016-08-19 | 1610-900-1151 | 3.72 ppb |
2016-08-19 | 1610-902-1026 | 5.46 ppb |
2016-08-19 | 1610-903-1142 | 4.11 ppb |
2016-08-19 | 1610-904-1110 | 4.73 ppb |
2016-08-19 | 1610-905-1313 | 5.39 ppb |
2016-08-19 | 1610-906-1350 | 2.97 ppb |
2016-08-19 | 1610-907-1330 | 3.17 ppb |
2016-08-19 | 1610-908-1130 | 6.19 ppb |
2016-08-19 | 1610-909-1343 | 1.68 ppb |
2016-08-19 | 1610-910-1410 | 6.60 ppb |
2016-08-19 | 1610-911-0829 | 3.58 ppb |
2016-08-19 | 1610-912-0915 | 3.52 ppb |
2016-08-19 | 1610-913-0946 | 6.99 ppb |
2016-08-19 | 1610-914-0938 | 6.68 ppb |
2016-08-19 | 1610-915-0855 | ND |
2016-11-01 | 1610-900-1041 | 1.47 ppb |
2016-11-01 | 1610-901-1145 | 1.34 ppb |
2016-11-01 | 1610-902-0943 | 3.89 ppb |
2016-11-01 | 1610-903-1032 | 1.39 ppb |
2016-11-01 | 1610-904-0954 | 3.50 ppb |
2016-11-01 | 1610-905-1117 | 1.57 ppb |
2016-11-01 | 1610-906-1050 | 1.49 ppb |
2016-11-01 | 1610-907-1130 | 1.29 ppb |
2016-11-01 | 1610-908-1013 | 3.05 ppb |
2016-11-01 | 1610-909-1103 | 2.00 ppb |
2016-11-01 | 1610-910-1231 | 3.77 ppb |
2016-11-01 | 1610-911-1207 | 1.42 ppb |
2016-11-01 | 1610-912-1432 | 1.50 ppb |
2016-11-01 | 1610-913-1357 | 2.11 ppb |
2016-11-01 | 1610-914-1412 | 1.62 ppb |
2016-11-01 | 1610-915-1245 | 1.42 ppb |
2017-02-10 | 1610-900-0836 | 2.77 ppb |
2017-02-10 | 1610-901-0915 | 1.40 ppb |
2017-02-10 | 1610-902-0743 | 4.24 ppb |
2017-02-10 | 1610-903-0826 | 2.16 ppb |
2017-02-10 | 1610-904-0750 | 4.10 ppb |
2017-02-10 | 1610-905-0850 | 1.58 ppb |
2017-02-10 | 1610-906-0943 | 2.43 ppb |
2017-02-10 | 1610-907-0902 | 1.38 ppb |
2017-02-10 | 1610-908-0811 | 21.3 ppb |
2017-02-10 | 1610-909-0933 | 1.84 ppb |
2017-02-10 | 1610-910-1000 | 6.26 ppb |
2017-02-10 | 1610-911-1046 | 1.72 ppb |
2017-02-10 | 1610-912-1230 | 1.88 ppb |
2017-02-10 | 1610-913-1300 | 1.61 ppb |
2017-02-10 | 1610-914-1300 | 2.17 ppb |
2017-02-10 | 1610-915-1011 | ND |
2017-05-15 | 1610-900-1016 | 12.0 ppb |
2017-05-15 | 1610-901-1345 | ND |
2017-05-15 | 1610-902-0903 | 22.2 ppb |
2017-05-15 | 1610-903-1007 | 13.2 ppb |
2017-05-15 | 1610-904-0915 | 15.8 ppb |
2017-05-15 | 1610-905-1317 | ND |
2017-05-15 | 1610-906-1032 | 16.4 ppb |
2017-05-15 | 1610-907-1329 | 1.21 ppb |
2017-05-15 | 1610-908-0938 | 13.6 ppb |
2017-05-15 | 1610-909-1023 | 1.04 ppb |
2017-05-15 | 1610-910-1115 | 22.6 ppb |
2017-05-15 | 1610-911-1252 | 24.1 ppb |
2017-05-15 | 1610-912-1414 | 37.2 ppb |
2017-05-15 | 1610-913-1445 | 11.5 ppb |
2017-05-15 | 1610-914-1435 | 34.6 ppb |
2017-05-15 | 1610-915-1028 | 6.07 ppb |
2017-08-14 | 1610-900-1011 | 6.77 ppb |
2017-08-14 | 1610-902-0919 | 8.20 ppb |
2017-08-14 | 1610-903-1000 | 6.81 ppb |
2017-08-14 | 1610-904-0930 | 8.47 ppb |
2017-08-14 | 1610-905-1050 | 1.36 ppb |
2017-08-14 | 1610-906-1023 | 6.11 ppb |
2017-08-14 | 1610-907-1111 | 1.28 ppb |
2017-08-14 | 1610-908-0948 | 12.5 ppb |
2017-08-14 | 1610-909-1300 | 0.770 ppb |
2017-08-14 | 1610-911-1235 | 3.62 ppb |
2017-08-14 | 1610-912-1318 | 4.08 ppb |
2017-08-14 | 1610-913-1407 | 12.2 ppb |
2017-08-14 | 1610-914-1343 | 15.2 ppb |
2017-08-14 | 1610-915-1255 | ND |
2017-11-01 | 1610-900-1009 | 17.3 ppb |
2017-11-01 | 1610-901-1125 | 1.81 ppb |
2017-11-01 | 1610-902-0915 | 19.9 ppb |
2017-11-01 | 1610-903-1002 | 18.2 ppb |
2017-11-01 | 1610-904-0900 | 17.4 ppb |
2017-11-01 | 1610-905-1043 | 1.88 ppb |
2017-11-01 | 1610-906-1032 | 17.7 ppb |
2017-11-01 | 1610-907-1051 | 2.38 ppb |
2017-11-01 | 1610-908-0950 | 15.6 ppb |
2017-11-01 | 1610-909-1023 | 2.07 ppb |
2017-11-01 | 1610-910-1201 | 17.4 ppb |
2017-11-01 | 1610-911-1255 | 14.2 ppb |
2017-11-01 | 1610-912-1337 | 14.6 ppb |
2017-11-01 | 1610-913-1410 | 12.9 ppb |
2017-11-01 | 1610-914-1400 | 11.3 ppb |
2017-11-01 | 1610-915-1317 | ND |
2018-02-12 | 1610-900-1058 | 4.57 ppb |
2018-02-12 | 1610-901-1243 | 10.2 ppb |
2018-02-12 | 1610-902-0931 | 9.20 ppb |
2018-02-12 | 1610-903-1050 | 5.60 ppb |
2018-02-12 | 1610-904-0940 | 10.3 ppb |
2018-02-12 | 1610-905-1213 | 12.3 ppb |
2018-02-12 | 1610-906-1119 | 8.23 ppb |
2018-02-12 | 1610-907-1227 | 6.94 ppb |
2018-02-12 | 1610-908-1011 | 9.04 ppb |
2018-02-12 | 1610-909-1146 | 13.2 ppb |
2018-02-12 | 1610-910-1302 | ND |
2018-02-12 | 1610-911-1337 | 2.17 ppb |
2018-02-12 | 1610-912-1416 | 8.53 ppb |
2018-02-12 | 1610-913-1449 | 6.83 ppb |
2018-02-12 | 1610-914-1441 | 6.88 ppb |
2018-02-12 | 1610-915-1315 | ND |
2018-05-07 | 1610-900-1022 | 11.3 ppb |
2018-05-07 | 1610-901-1150 | 11.4 ppb |
2018-05-07 | 1610-902-0918 | 9.30 ppb |
2018-05-07 | 1610-903-1014 | 11.5 ppb |
2018-05-07 | 1610-904-0929 | 5.71 ppb |
2018-05-07 | 1610-905-1121 | 11.2 ppb |
2018-05-07 | 1610-906-1045 | 13.5 ppb |
2018-05-07 | 1610-907-1130 | 4.76 ppb |
2018-05-07 | 1610-908-0955 | 14.3 ppb |
2018-05-07 | 1610-909-1036 | 14.3 ppb |
2018-05-07 | 1610-910-1207 | 5.23 ppb |
2018-05-07 | 1610-911-1314 | 2.82 ppb |
2018-05-07 | 1610-913-1348 | 8.95 ppb |
2018-05-07 | 1610-914-1405 | 15.1 ppb |
2018-05-07 | 1610-915-1217 | ND |
2018-05-08 | 1610-912-1254 | 3.38 ppb |
2018-08-02 | 1610-900-1004 | 15.6 ppb |
2018-08-02 | 1610-901-1105 | 21.9 ppb |
2018-08-02 | 1610-902-0910 | 9.27 ppb |
2018-08-02 | 1610-903-0954 | 6.94 ppb |
2018-08-02 | 1610-904-0920 | 8.70 ppb |
2018-08-02 | 1610-905-1046 | 22.1 ppb |
2018-08-02 | 1610-906-1038 | 16.3 ppb |
2018-08-02 | 1610-907-1055 | 12.9 ppb |
2018-08-02 | 1610-908-0941 | 7.87 ppb |
2018-08-02 | 1610-909-1021 | 21.4 ppb |
2018-08-02 | 1610-910-1139 | 8.39 ppb |
2018-08-02 | 1610-911-1300 | 3.22 ppb |
2018-08-02 | 1610-912-1331 | 5.61 ppb |
2018-08-02 | 1610-913-1410 | 13.1 ppb |
2018-08-02 | 1610-914-1400 | 12.1 ppb |
2018-08-02 | 1610-915-1236 | ND |
2018-11-05 | 1610-900-1055 | 11.0 ppb |
2018-11-05 | 1610-901-1230 | 17.4 ppb |
2018-11-05 | 1610-902-0935 | 5.20 ppb |
2018-11-05 | 1610-903-1045 | 12.1 ppb |
2018-11-05 | 1610-904-0947 | 5.83 ppb |
2018-11-05 | 1610-905-1156 | 18.4 ppb |
2018-11-05 | 1610-906-1119 | 15.4 ppb |
2018-11-05 | 1610-907-1204 | 8.69 ppb |
2018-11-05 | 1610-908-1011 | 4.88 ppb |
2018-11-05 | 1610-909-1109 | 18.3 ppb |
2018-11-05 | 1610-910-1358 | 6.03 ppb |
2018-11-05 | 1610-911-1418 | 1.14 ppb |
2018-11-05 | 1610-915-1342 | ND |
2018-11-06 | 1610-912-1138 | 1.59 ppb |
2018-11-06 | 1610-913-1430 | 7.01 ppb |
2018-11-06 | 1610-914-1415 | 8.20 ppb |
2019-02-11 | 1610-900-1107 | 13.0 ppb |
2019-02-11 | 1610-901-1219 | 11.8 ppb |
2019-02-11 | 1610-902-0842 | 12.4 ppb |
2019-02-11 | 1610-903-1055 | 15.7 ppb |
2019-02-11 | 1610-904-0902 | 14.1 ppb |
2019-02-11 | 1610-905-1139 | 12.4 ppb |
2019-02-11 | 1610-906-1339 | 14.2 ppb |
2019-02-11 | 1610-907-1200 | 8.89 ppb |
2019-02-11 | 1610-908-1007 | 15.8 ppb |
2019-02-11 | 1610-909-1237 | 14.2 ppb |
2019-02-11 | 1610-910-1401 | 6.71 ppb |
2019-02-11 | 1610-915-1424 | 12.8 ppb |
2019-02-12 | 1610-911-0955 | 6.46 ppb |
2019-02-12 | 1610-912-1119 | 11.2 ppb |
2019-02-12 | 1610-913-1335 | 6.51 ppb |
2019-02-12 | 1610-914-1320 | 6.92 ppb |
2019-05-08 | 1610-900-1030 | 14.9 ppb |
2019-05-08 | 1610-901-1145 | 16.2 ppb |
2019-05-08 | 1610-902-0915 | 5.28 ppb |
2019-05-08 | 1610-903-1020 | 18.7 ppb |
2019-05-08 | 1610-904-0931 | 5.13 ppb |
2019-05-08 | 1610-905-1120 | 16.6 ppb |
2019-05-08 | 1610-906-1100 | 16.5 ppb |
2019-05-08 | 1610-907-1135 | 6.93 ppb |
2019-05-08 | 1610-908-0951 | 42.6 ppb |
2019-05-08 | 1610-909-1045 | 16.5 ppb |
2019-05-08 | 1610-910-1235 | 6.45 ppb |
2019-05-08 | 1610-911-1215 | 1.94 ppb |
2019-05-08 | 1610-912-1310 | 2.74 ppb |
2019-05-08 | 1610-913-1415 | 22.1 ppb |
2019-05-08 | 1610-914-1345 | 16.7 ppb |
2019-05-08 | 1610-915-1247 | 1.38 ppb |
2019-08-14 | 1610-900-0709 | 16.0 ppb |
2019-08-14 | 1610-901-0812 | 15.9 ppb |
2019-08-14 | 1610-902-0600 | 5.60 ppb |
2019-08-14 | 1610-903-0700 | 15.1 ppb |
2019-08-14 | 1610-904-1046 | 5.75 ppb |
2019-08-14 | 1610-905-0752 | 14.5 ppb |
2019-08-14 | 1610-906-0743 | 16.7 ppb |
2019-08-14 | 1610-907-0800 | 7.86 ppb |
2019-08-14 | 1610-908-0639 | 7.51 ppb |
2019-08-14 | 1610-909-0724 | 16.8 ppb |
2019-08-14 | 1610-910-0836 | 12.9 ppb |
2019-08-14 | 1610-911-0907 | 1.41 ppb |
2019-08-14 | 1610-912-1028 | 3.87 ppb |
2019-08-14 | 1610-913-1123 | 11.8 ppb |
2019-08-14 | 1610-914-1100 | 10.7 ppb |
2019-08-14 | 1610-915-0848 | ND |
2019-11-20 | 1610-900-1130 | 12.8 ppb |
2019-11-20 | 1610-901-1028 | 19.6 ppb |
2019-11-20 | 1610-902-1011 | 21.8 ppb |
2019-11-20 | 1610-903-1120 | 11.2 ppb |
2019-11-20 | 1610-904-0922 | 15.0 ppb |
2019-11-20 | 1610-905-0953 | 19.1 ppb |
2019-11-20 | 1610-906-1059 | 13.2 ppb |
2019-11-20 | 1610-907-1008 | 12.5 ppb |
2019-11-20 | 1610-908-0929 | 1.51 ppb |
2019-11-20 | 1610-909-1047 | 15.7 ppb |
2019-11-20 | 1610-910-1121 | 10.3 ppb |
2019-11-20 | 1610-911-1150 | 1.47 ppb |
2019-11-20 | 1610-912-1408 | 5.52 ppb |
2019-11-20 | 1610-913-1420 | 15.1 ppb |
2019-11-20 | 1610-914-1400 | 13.2 ppb |
2019-11-20 | 1610-915-1311 | ND |