Chloroform
Pomona Water Department
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.
304
Samples
0
Samples exceeding legal limit (MCL)
232
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 | 2.98 ppb | 54 | 39 | ND - 12.0 ppb |
| 2015 | 3.74 ppb | 52 | 41 | ND - 14.0 ppb |
| 2016 | 5.07 ppb | 47 | 37 | ND - 17.0 ppb |
| 2017 | 6.29 ppb | 50 | 38 | ND - 25.0 ppb |
| 2018 | 3.47 ppb | 49 | 38 | ND - 19.0 ppb |
| 2019 | 4.15 ppb | 52 | 39 | ND - 17.0 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 |
|---|---|---|
| 2014-01-02 | 9590-031-1129 | 3.60 ppb |
| 2014-01-02 | 9590-042-1105 | 7.40 ppb |
| 2014-01-06 | 9590-033-1012 | 3.00 ppb |
| 2014-01-06 | 9590-038-1046 | ND |
| 2014-01-06 | 9590-069-1037 | ND |
| 2014-01-08 | 9590-010-0912 | ND |
| 2014-01-16 | 9590-025-0838 | ND |
| 2014-01-16 | 9590-040-0902 | ND |
| 2014-02-11 | 9590-800-0738 | 1.30 ppb |
| 2014-02-11 | 9590-801-0849 | 2.10 ppb |
| 2014-02-11 | 9590-802-0916 | 1.90 ppb |
| 2014-02-11 | 9590-803-1005 | 1.20 ppb |
| 2014-02-11 | 9590-804-0943 | ND |
| 2014-02-11 | 9590-805-0830 | 1.80 ppb |
| 2014-02-11 | 9590-806-1027 | ND |
| 2014-02-11 | 9590-807-0803 | 1.40 ppb |
| 2014-02-19 | 9590-051-1311 | ND |
| 2014-03-18 | 9590-013-0955 | ND |
| 2014-03-26 | 9590-036-0957 | 7.30 ppb |
| 2014-04-09 | 9590-071-0935 | ND |
| 2014-05-13 | 9590-800-0803 | 2.90 ppb |
| 2014-05-13 | 9590-801-0917 | 4.30 ppb |
| 2014-05-13 | 9590-802-0941 | 5.30 ppb |
| 2014-05-13 | 9590-803-1029 | 3.20 ppb |
| 2014-05-13 | 9590-804-1052 | 2.20 ppb |
| 2014-05-13 | 9590-805-0858 | 4.90 ppb |
| 2014-05-13 | 9590-806-1009 | 4.10 ppb |
| 2014-05-13 | 9590-807-0830 | 2.60 ppb |
| 2014-06-10 | 9590-028-0740 | 1.40 ppb |
| 2014-07-02 | 9590-032-0813 | 2.30 ppb |
| 2014-07-07 | 9590-033-0847 | 8.00 ppb |
| 2014-07-07 | 9590-038-0945 | ND |
| 2014-07-07 | 9590-042-1135 | 4.50 ppb |
| 2014-07-16 | 9590-052-0856 | ND |
| 2014-08-12 | 9590-800-0823 | 6.90 ppb |
| 2014-08-12 | 9590-801-0930 | 12.0 ppb |
| 2014-08-12 | 9590-802-0800 | 8.40 ppb |
| 2014-08-12 | 9590-803-0858 | 3.40 ppb |
| 2014-08-12 | 9590-804-0925 | 2.90 ppb |
| 2014-08-12 | 9590-805-0910 | 7.00 ppb |
| 2014-08-12 | 9590-806-0830 | 8.20 ppb |
| 2014-08-12 | 9590-807-0847 | 5.80 ppb |
| 2014-08-28 | 9590-027-0930 | ND |
| 2014-10-06 | 9590-071-0918 | ND |
| 2014-11-12 | 9590-051-1005 | ND |
| 2014-11-12 | 9590-800-0742 | 1.50 ppb |
| 2014-11-12 | 9590-801-0845 | 1.90 ppb |
| 2014-11-12 | 9590-802-0910 | 5.50 ppb |
| 2014-11-12 | 9590-803-0951 | 2.60 ppb |
| 2014-11-12 | 9590-804-1017 | 8.40 ppb |
| 2014-11-12 | 9590-805-0829 | 3.20 ppb |
| 2014-11-12 | 9590-806-0934 | 1.50 ppb |
| 2014-11-12 | 9590-807-0802 | 2.00 ppb |
| 2014-12-09 | 9590-035-0943 | 3.00 ppb |
| 2015-01-05 | 9590-033-1052 | 2.40 ppb |
| 2015-01-05 | 9590-038-0946 | ND |
| 2015-01-05 | 9590-042-1030 | 9.40 ppb |
| 2015-01-05 | 9590-069-0943 | ND |
| 2015-01-13 | 9590-010-0834 | ND |
| 2015-01-13 | 9590-025-0930 | ND |
| 2015-01-13 | 9590-040-0930 | ND |
| 2015-02-09 | 9590-800-0833 | 2.10 ppb |
| 2015-02-09 | 9590-801-0938 | 2.00 ppb |
| 2015-02-09 | 9590-802-1000 | 3.40 ppb |
| 2015-02-09 | 9590-803-1047 | 10.00 ppb |
| 2015-02-09 | 9590-804-1113 | 8.40 ppb |
| 2015-02-09 | 9590-805-0922 | 2.20 ppb |
| 2015-02-09 | 9590-806-1023 | 3.20 ppb |
| 2015-02-09 | 9590-807-0900 | 2.20 ppb |
| 2015-02-26 | 9590-036-0922 | 14.0 ppb |
| 2015-03-23 | 9590-031-1000 | 6.50 ppb |
| 2015-04-06 | 9590-071-1131 | ND |
| 2015-04-14 | 9590-013-0935 | ND |
| 2015-05-12 | 9590-800-0744 | 4.20 ppb |
| 2015-05-12 | 9590-801-0847 | 8.10 ppb |
| 2015-05-12 | 9590-802-0905 | 7.20 ppb |
| 2015-05-12 | 9590-803-0950 | 3.40 ppb |
| 2015-05-12 | 9590-804-1014 | 2.30 ppb |
| 2015-05-12 | 9590-805-0829 | 6.30 ppb |
| 2015-05-12 | 9590-806-0924 | 2.30 ppb |
| 2015-05-12 | 9590-807-0806 | 4.20 ppb |
| 2015-06-10 | 9590-028-0844 | 1.60 ppb |
| 2015-07-01 | 9590-052-1029 | ND |
| 2015-07-06 | 9590-033-0910 | 8.00 ppb |
| 2015-07-06 | 9590-038-0857 | ND |
| 2015-07-06 | 9590-042-0959 | 8.20 ppb |
| 2015-07-08 | 9590-032-0815 | 3.60 ppb |
| 2015-08-11 | 9590-800-0800 | 6.60 ppb |
| 2015-08-11 | 9590-801-0916 | 6.40 ppb |
| 2015-08-11 | 9590-802-0939 | 8.00 ppb |
| 2015-08-11 | 9590-803-1029 | 2.60 ppb |
| 2015-08-11 | 9590-804-1052 | 1.30 ppb |
| 2015-08-11 | 9590-805-0848 | 7.40 ppb |
| 2015-08-11 | 9590-806-1009 | 1.20 ppb |
| 2015-08-11 | 9590-807-0823 | 4.00 ppb |
| 2015-09-29 | 9590-027-1145 | ND |
| 2015-10-05 | 9590-071-1040 | ND |
| 2015-10-20 | 9590-035-1021 | 6.20 ppb |
| 2015-11-10 | 9590-800-1022 | 3.20 ppb |
| 2015-11-10 | 9590-801-0928 | 3.20 ppb |
| 2015-11-10 | 9590-802-0900 | 2.90 ppb |
| 2015-11-10 | 9590-803-0814 | 3.60 ppb |
| 2015-11-10 | 9590-804-0747 | 5.00 ppb |
| 2015-11-10 | 9590-805-0951 | 3.10 ppb |
| 2015-11-10 | 9590-806-0836 | 2.20 ppb |
| 2015-11-10 | 9590-807-1045 | 2.60 ppb |
| 2016-01-04 | 9590-042-1250 | 6.60 ppb |
| 2016-01-06 | 9590-025-0920 | ND |
| 2016-01-06 | 9590-040-0830 | ND |
| 2016-01-12 | 9590-031-0824 | 4.50 ppb |
| 2016-01-12 | 9590-036-0850 | 17.0 ppb |
| 2016-01-13 | 9590-010-1000 | ND |
| 2016-02-09 | 9590-800-1020 | 2.20 ppb |
| 2016-02-09 | 9590-801-0928 | 2.50 ppb |
| 2016-02-09 | 9590-802-0828 | 3.40 ppb |
| 2016-02-09 | 9590-803-0751 | 6.10 ppb |
| 2016-02-09 | 9590-804-0925 | 9.60 ppb |
| 2016-02-09 | 9590-805-0951 | 2.70 ppb |
| 2016-02-09 | 9590-806-0856 | 3.60 ppb |
| 2016-02-09 | 9590-807-1047 | 2.30 ppb |
| 2016-04-04 | 9590-071-1009 | ND |
| 2016-05-10 | 9590-800-0735 | 6.90 ppb |
| 2016-05-10 | 9590-801-0848 | 8.50 ppb |
| 2016-05-10 | 9590-802-0920 | 6.60 ppb |
| 2016-05-10 | 9590-803-1013 | 7.20 ppb |
| 2016-05-10 | 9590-804-1037 | 5.70 ppb |
| 2016-05-10 | 9590-805-0825 | 7.70 ppb |
| 2016-05-10 | 9590-806-0950 | 2.80 ppb |
| 2016-05-10 | 9590-807-0800 | 5.90 ppb |
| 2016-06-02 | 9590-028-1115 | 4.50 ppb |
| 2016-07-05 | 9590-038-0954 | ND |
| 2016-07-05 | 9590-052-1111 | ND |
| 2016-07-14 | 9590-033-1000 | 9.40 ppb |
| 2016-07-14 | 9590-042-0845 | 4.80 ppb |
| 2016-07-20 | 9590-027-0945 | ND |
| 2016-08-09 | 9590-800-0714 | 9.90 ppb |
| 2016-08-09 | 9590-801-0909 | 11.0 ppb |
| 2016-08-09 | 9590-802-0805 | 11.0 ppb |
| 2016-08-09 | 9590-803-0910 | 4.20 ppb |
| 2016-08-09 | 9590-804-0940 | 2.60 ppb |
| 2016-08-09 | 9590-805-0837 | 9.60 ppb |
| 2016-08-09 | 9590-806-0843 | 11.0 ppb |
| 2016-08-09 | 9590-807-0745 | 9.00 ppb |
| 2016-08-25 | 9590-806-1055 | 7.90 ppb |
| 2016-10-12 | 9590-071-0942 | ND |
| 2016-11-09 | 9590-800-1010 | 6.00 ppb |
| 2016-11-09 | 9590-801-1131 | 4.60 ppb |
| 2016-11-09 | 9590-802-1355 | 5.30 ppb |
| 2016-11-09 | 9590-803-1508 | ND |
| 2016-11-09 | 9590-804-1515 | ND |
| 2016-11-09 | 9590-805-1107 | 6.80 ppb |
| 2016-11-09 | 9590-806-1425 | 2.80 ppb |
| 2016-11-09 | 9590-807-1035 | 6.10 ppb |
| 2017-01-03 | 9590-031-1213 | 5.20 ppb |
| 2017-01-03 | 9590-033-0933 | 6.20 ppb |
| 2017-01-03 | 9590-038-0835 | ND |
| 2017-01-10 | 9590-069-1103 | ND |
| 2017-01-17 | 9590-010-1205 | ND |
| 2017-01-18 | 9590-025-1218 | ND |
| 2017-01-18 | 9590-040-1133 | ND |
| 2017-01-25 | 9590-051-0910 | ND |
| 2017-02-07 | 9590-800-1302 | 3.80 ppb |
| 2017-02-07 | 9590-801-1425 | 6.80 ppb |
| 2017-02-07 | 9590-802-1540 | 5.60 ppb |
| 2017-02-07 | 9590-803-1400 | ND |
| 2017-02-07 | 9590-804-1425 | ND |
| 2017-02-07 | 9590-805-1405 | 6.60 ppb |
| 2017-02-07 | 9590-806-1255 | 1.10 ppb |
| 2017-02-07 | 9590-807-1338 | 3.80 ppb |
| 2017-03-09 | 9590-042-1005 | 13.0 ppb |
| 2017-04-06 | 9590-071-1145 | ND |
| 2017-05-11 | 9590-800-0825 | 20.0 ppb |
| 2017-05-11 | 9590-801-0836 | 25.0 ppb |
| 2017-05-11 | 9590-802-0935 | 14.0 ppb |
| 2017-05-11 | 9590-803-1037 | 9.70 ppb |
| 2017-05-11 | 9590-804-1106 | 8.40 ppb |
| 2017-05-11 | 9590-805-0755 | 25.0 ppb |
| 2017-05-11 | 9590-806-1003 | 8.00 ppb |
| 2017-05-11 | 9590-807-1054 | 18.0 ppb |
| 2017-05-17 | 9590-036-1045 | 9.90 ppb |
| 2017-07-11 | 9590-028-0910 | 2.20 ppb |
| 2017-07-11 | 9590-038-1040 | ND |
| 2017-07-13 | 9590-033-0930 | 10.00 ppb |
| 2017-07-13 | 9590-042-1150 | 3.30 ppb |
| 2017-07-24 | 9590-027-1415 | ND |
| 2017-07-25 | 9590-052-1445 | ND |
| 2017-08-08 | 9590-800-0804 | 13.0 ppb |
| 2017-08-08 | 9590-801-0920 | 13.0 ppb |
| 2017-08-08 | 9590-802-0941 | 13.0 ppb |
| 2017-08-08 | 9590-803-1042 | 5.80 ppb |
| 2017-08-08 | 9590-804-1106 | 6.00 ppb |
| 2017-08-08 | 9590-805-0858 | 13.0 ppb |
| 2017-08-08 | 9590-806-1010 | 3.10 ppb |
| 2017-08-08 | 9590-807-0832 | 13.0 ppb |
| 2017-10-25 | 9590-032-1115 | 4.40 ppb |
| 2017-11-15 | 9590-800-0920 | 2.60 ppb |
| 2017-11-15 | 9590-801-1045 | 3.20 ppb |
| 2017-11-15 | 9590-802-1314 | 2.40 ppb |
| 2017-11-15 | 9590-803-1415 | 3.60 ppb |
| 2017-11-15 | 9590-804-1445 | 5.10 ppb |
| 2017-11-15 | 9590-805-1020 | 2.80 ppb |
| 2017-11-15 | 9590-806-1340 | 2.40 ppb |
| 2017-11-15 | 9590-807-0945 | 2.70 ppb |
| 2018-01-03 | 9590-033-1405 | 2.20 ppb |
| 2018-01-03 | 9590-038-1006 | ND |
| 2018-01-18 | 9590-042-1313 | 6.80 ppb |
| 2018-01-22 | 9590-010-1207 | ND |
| 2018-01-22 | 9590-025-1257 | ND |
| 2018-01-22 | 9590-040-1325 | ND |
| 2018-01-23 | 9590-069-1404 | ND |
| 2018-02-08 | 9590-800-1034 | 3.10 ppb |
| 2018-02-08 | 9590-801-1152 | 3.70 ppb |
| 2018-02-08 | 9590-802-1300 | 4.80 ppb |
| 2018-02-08 | 9590-803-1358 | 4.70 ppb |
| 2018-02-08 | 9590-804-1427 | ND |
| 2018-02-08 | 9590-805-1129 | 3.90 ppb |
| 2018-02-08 | 9590-806-1332 | 4.50 ppb |
| 2018-02-08 | 9590-807-1100 | 3.30 ppb |
| 2018-04-16 | 9590-071-0956 | ND |
| 2018-05-16 | 9590-800-0912 | 2.00 ppb |
| 2018-05-16 | 9590-801-1116 | 3.60 ppb |
| 2018-05-16 | 9590-802-1157 | 1.20 ppb |
| 2018-05-16 | 9590-803-0948 | 6.80 ppb |
| 2018-05-16 | 9590-804-1015 | 7.50 ppb |
| 2018-05-16 | 9590-805-1049 | 3.60 ppb |
| 2018-05-16 | 9590-806-0900 | 3.10 ppb |
| 2018-05-16 | 9590-807-1016 | 2.30 ppb |
| 2018-05-23 | 9590-028-1006 | 2.20 ppb |
| 2018-06-13 | 9590-063-0955 | 8.40 ppb |
| 2018-07-11 | 9590-033-1309 | 5.90 ppb |
| 2018-07-16 | 9590-038-1333 | ND |
| 2018-07-17 | 9590-042-1055 | 5.00 ppb |
| 2018-07-18 | 9590-027-1408 | ND |
| 2018-07-19 | 9590-031-0951 | 7.00 ppb |
| 2018-08-15 | 9590-800-0751 | 6.70 ppb |
| 2018-08-15 | 9590-801-0915 | 6.00 ppb |
| 2018-08-15 | 9590-802-0948 | 4.90 ppb |
| 2018-08-15 | 9590-803-1307 | 2.40 ppb |
| 2018-08-15 | 9590-804-1058 | ND |
| 2018-08-15 | 9590-805-0855 | 7.10 ppb |
| 2018-08-15 | 9590-806-1018 | 4.50 ppb |
| 2018-08-15 | 9590-807-0825 | 4.50 ppb |
| 2018-10-23 | 9590-071-0935 | ND |
| 2018-11-14 | 9590-800-0803 | 2.20 ppb |
| 2018-11-14 | 9590-801-0953 | 3.50 ppb |
| 2018-11-14 | 9590-802-1042 | 2.40 ppb |
| 2018-11-14 | 9590-803-1340 | 2.00 ppb |
| 2018-11-14 | 9590-804-1305 | 1.80 ppb |
| 2018-11-14 | 9590-805-0922 | 3.40 ppb |
| 2018-11-14 | 9590-806-1115 | 1.60 ppb |
| 2018-11-14 | 9590-807-0850 | 2.60 ppb |
| 2018-12-06 | 9590-063-0820 | 19.0 ppb |
| 2019-01-03 | 9590-010-0939 | ND |
| 2019-01-09 | 9590-033-1045 | 1.60 ppb |
| 2019-01-09 | 9590-069-1121 | ND |
| 2019-01-23 | 9590-010-1045 | ND |
| 2019-01-23 | 9590-038-0843 | ND |
| 2019-01-24 | 9590-025-1116 | ND |
| 2019-01-24 | 9590-040-1155 | ND |
| 2019-01-29 | 9590-042-1256 | 8.00 ppb |
| 2019-01-30 | 9590-032-0915 | 2.70 ppb |
| 2019-02-12 | 9590-800-0842 | ND |
| 2019-02-12 | 9590-801-1020 | ND |
| 2019-02-12 | 9590-802-1058 | 1.90 ppb |
| 2019-02-12 | 9590-803-1207 | 1.80 ppb |
| 2019-02-12 | 9590-804-1205 | 1.30 ppb |
| 2019-02-12 | 9590-805-0950 | 1.40 ppb |
| 2019-02-12 | 9590-806-1132 | 1.80 ppb |
| 2019-02-12 | 9590-807-0922 | 1.10 ppb |
| 2019-04-04 | 9590-071-0901 | ND |
| 2019-04-17 | 9590-035-1010 | 4.10 ppb |
| 2019-04-17 | 9590-036-1005 | 7.70 ppb |
| 2019-04-17 | 9590-051-1110 | ND |
| 2019-04-17 | 9590-063-1354 | 17.0 ppb |
| 2019-05-16 | 9590-800-1526 | 7.70 ppb |
| 2019-05-16 | 9590-801-1512 | 5.80 ppb |
| 2019-05-16 | 9590-802-1425 | 5.70 ppb |
| 2019-05-16 | 9590-803-1250 | 8.00 ppb |
| 2019-05-16 | 9590-804-1215 | 7.90 ppb |
| 2019-05-16 | 9590-805-1422 | 6.20 ppb |
| 2019-05-16 | 9590-806-1325 | 7.40 ppb |
| 2019-05-16 | 9590-807-1503 | 7.60 ppb |
| 2019-07-02 | 9590-042-1220 | 3.10 ppb |
| 2019-07-18 | 9590-027-1156 | ND |
| 2019-07-18 | 9590-031-1035 | 6.60 ppb |
| 2019-07-18 | 9590-052-1330 | ND |
| 2019-08-12 | 9590-800-1159 | 5.40 ppb |
| 2019-08-12 | 9590-801-1342 | 5.60 ppb |
| 2019-08-12 | 9590-802-0906 | 4.60 ppb |
| 2019-08-12 | 9590-803-1023 | 6.00 ppb |
| 2019-08-12 | 9590-804-1150 | 7.30 ppb |
| 2019-08-12 | 9590-805-1103 | 5.30 ppb |
| 2019-08-12 | 9590-806-1233 | 2.10 ppb |
| 2019-08-12 | 9590-807-1033 | 5.00 ppb |
| 2019-10-03 | 9590-063-1340 | 9.60 ppb |
| 2019-10-10 | 9590-071-1316 | ND |
| 2019-11-12 | 9590-800-1210 | 3.60 ppb |
| 2019-11-12 | 9590-801-1339 | 3.50 ppb |
| 2019-11-12 | 9590-802-0938 | 1.80 ppb |
| 2019-11-12 | 9590-803-1115 | 12.0 ppb |
| 2019-11-12 | 9590-804-1245 | 15.0 ppb |
| 2019-11-12 | 9590-805-1412 | 2.60 ppb |
| 2019-11-12 | 9590-806-1325 | 6.60 ppb |
| 2019-11-12 | 9590-807-1447 | 3.60 ppb |