Chloroform
Metropolitan Utilities 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 | 17.5 ppb | 58 | 56 | ND - 32.0 ppb |
2015 | 20.1 ppb | 52 | 50 | ND - 44.0 ppb |
2016 | 20.7 ppb | 53 | 51 | ND - 33.9 ppb |
2017 | 18.0 ppb | 61 | 52 | ND - 53.0 ppb |
2018 | 24.2 ppb | 50 | 50 | 10.3 ppb - 48.6 ppb |
2019 | 30.7 ppb | 51 | 50 | ND - 57.6 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 |
---|---|---|
2014-01-08 | 294497 | 20.1 ppb |
2014-02-04 | 283310 | 13.6 ppb |
2014-02-04 | 283311 | 9.13 ppb |
2014-02-04 | 283312 | 11.9 ppb |
2014-02-04 | 283313 | 13.8 ppb |
2014-02-04 | 283315 | 13.9 ppb |
2014-02-04 | 283321 | 17.6 ppb |
2014-02-11 | 287613 | 10.3 ppb |
2014-02-11 | 287615 | 12.1 ppb |
2014-02-11 | 287616 | 14.1 ppb |
2014-02-11 | 287617 | 13.8 ppb |
2014-02-11 | 287618 | 11.0 ppb |
2014-02-11 | 287619 | 11.7 ppb |
2014-04-08 | 293527 | 0.784 ppb |
2014-05-05 | 295285 | 18.3 ppb |
2014-05-05 | 295286 | 7.74 ppb |
2014-05-05 | 295287 | 20.6 ppb |
2014-05-05 | 295288 | 17.4 ppb |
2014-05-05 | 295289 | 16.8 ppb |
2014-05-05 | 295290 | 14.2 ppb |
2014-05-05 | 295291 | 23.1 ppb |
2014-05-05 | 295280 | 18.9 ppb |
2014-05-05 | 295281 | 19.1 ppb |
2014-05-05 | 295282 | 18.5 ppb |
2014-05-05 | 295283 | 7.07 ppb |
2014-05-05 | 295284 | 17.8 ppb |
2014-05-12 | 302599 | 8.88 ppb |
2014-06-02 | 294498 | ND |
2014-07-08 | 309807 | 1.24 ppb |
2014-08-05 | 311982 | 32.0 ppb |
2014-08-05 | 311983 | 31.8 ppb |
2014-08-05 | 311984 | 28.3 ppb |
2014-08-05 | 311985 | 31.7 ppb |
2014-08-05 | 311986 | 29.2 ppb |
2014-08-05 | 311987 | 28.5 ppb |
2014-08-05 | 311988 | 24.3 ppb |
2014-08-05 | 311989 | 24.4 ppb |
2014-08-05 | 311990 | 29.9 ppb |
2014-08-05 | 311991 | 29.8 ppb |
2014-08-05 | 311980 | 29.8 ppb |
2014-08-05 | 311981 | 31.4 ppb |
2014-08-26 | 311210 | 5.34 ppb |
2014-08-26 | 311212 | 22.2 ppb |
2014-08-26 | 311213 | 9.35 ppb |
2014-08-26 | 311214 | ND |
2014-09-02 | 324809 | 2.27 ppb |
2014-11-03 | 332925 | 21.3 ppb |
2014-11-03 | 332926 | 17.2 ppb |
2014-11-03 | 332927 | 20.3 ppb |
2014-11-03 | 332928 | 14.8 ppb |
2014-11-03 | 332929 | 21.8 ppb |
2014-11-03 | 332930 | 21.2 ppb |
2014-11-03 | 332931 | 22.5 ppb |
2014-11-03 | 332932 | 18.2 ppb |
2014-11-03 | 332933 | 22.7 ppb |
2014-11-03 | 332934 | 20.8 ppb |
2014-11-03 | 332935 | 17.1 ppb |
2014-11-03 | 332936 | 20.7 ppb |
2015-02-02 | 346549 | 9.13 ppb |
2015-02-02 | 346554 | 23.4 ppb |
2015-02-02 | 346555 | 15.7 ppb |
2015-02-02 | 346556 | 18.1 ppb |
2015-02-02 | 346557 | 19.6 ppb |
2015-02-02 | 346546 | 17.4 ppb |
2015-02-02 | 346547 | 16.7 ppb |
2015-02-02 | 346548 | 17.4 ppb |
2015-02-02 | 346550 | 19.0 ppb |
2015-02-02 | 346551 | 18.5 ppb |
2015-02-02 | 346552 | 8.96 ppb |
2015-02-02 | 346553 | 17.6 ppb |
2015-04-07 | 353665 | 8.35 ppb |
2015-04-07 | 353666 | 23.8 ppb |
2015-04-07 | 353667 | ND |
2015-05-05 | 361733 | 16.9 ppb |
2015-05-05 | 361736 | 11.7 ppb |
2015-05-05 | 361737 | 10.7 ppb |
2015-05-05 | 361738 | 18.9 ppb |
2015-05-05 | 361739 | 13.3 ppb |
2015-05-05 | 361730 | 7.74 ppb |
2015-05-05 | 361734 | 9.78 ppb |
2015-05-05 | 361735 | 16.6 ppb |
2015-05-05 | 361728 | 11.7 ppb |
2015-05-05 | 361729 | 16.8 ppb |
2015-05-05 | 361731 | 16.1 ppb |
2015-05-05 | 361732 | 8.45 ppb |
2015-07-07 | 371752 | ND |
2015-08-03 | 374544 | 28.0 ppb |
2015-08-03 | 374545 | 22.0 ppb |
2015-08-03 | 374549 | 35.0 ppb |
2015-08-03 | 374538 | 42.0 ppb |
2015-08-03 | 374539 | 34.0 ppb |
2015-08-03 | 374540 | 42.0 ppb |
2015-08-03 | 374541 | 22.0 ppb |
2015-08-03 | 374542 | 34.0 ppb |
2015-08-03 | 374543 | 39.0 ppb |
2015-08-03 | 374546 | 44.0 ppb |
2015-08-03 | 374547 | 37.0 ppb |
2015-08-03 | 374548 | 33.0 ppb |
2015-11-04 | 393708 | 18.8 ppb |
2015-11-04 | 393709 | 22.1 ppb |
2015-11-04 | 393710 | 21.9 ppb |
2015-11-04 | 393711 | 14.4 ppb |
2015-11-04 | 393712 | 23.2 ppb |
2015-11-04 | 393713 | 21.4 ppb |
2015-11-04 | 393714 | 22.0 ppb |
2015-11-04 | 393715 | 24.0 ppb |
2015-11-04 | 393716 | 18.1 ppb |
2015-11-04 | 393717 | 18.0 ppb |
2015-11-04 | 393718 | 21.1 ppb |
2015-11-04 | 393707 | 14.9 ppb |
2016-02-01 | 13.4 ppb | |
2016-02-01 | 11.5 ppb | |
2016-02-01 | 19.9 ppb | |
2016-02-01 | 19.1 ppb | |
2016-02-01 | 19.8 ppb | |
2016-02-01 | 18.2 ppb | |
2016-02-01 | 18.6 ppb | |
2016-02-01 | 19.0 ppb | |
2016-02-01 | 18.4 ppb | |
2016-02-01 | 16.9 ppb | |
2016-02-01 | 18.3 ppb | |
2016-02-01 | 18.1 ppb | |
2016-04-04 | ND | |
2016-04-18 | 8.05 ppb | |
2016-04-18 | 23.8 ppb | |
2016-05-02 | 27.2 ppb | |
2016-05-02 | 15.2 ppb | |
2016-05-02 | 31.0 ppb | |
2016-05-02 | 33.9 ppb | |
2016-05-02 | 29.2 ppb | |
2016-05-02 | 30.0 ppb | |
2016-05-02 | 26.8 ppb | |
2016-05-02 | 29.3 ppb | |
2016-05-02 | 13.4 ppb | |
2016-05-02 | 24.6 ppb | |
2016-05-02 | 23.8 ppb | |
2016-05-02 | 17.4 ppb | |
2016-05-02 | 29.0 ppb | |
2016-07-25 | ND | |
2016-08-02 | 29.2 ppb | |
2016-08-02 | 30.8 ppb | |
2016-08-02 | 29.2 ppb | |
2016-08-02 | 28.3 ppb | |
2016-08-02 | 26.4 ppb | |
2016-08-02 | 29.3 ppb | |
2016-08-02 | 28.4 ppb | |
2016-08-02 | 21.1 ppb | |
2016-08-02 | 29.2 ppb | |
2016-08-02 | 24.6 ppb | |
2016-08-02 | 27.8 ppb | |
2016-08-02 | 26.4 ppb | |
2016-11-07 | 17.6 ppb | |
2016-11-07 | 18.2 ppb | |
2016-11-07 | 17.7 ppb | |
2016-11-07 | 12.9 ppb | |
2016-11-07 | 15.5 ppb | |
2016-11-07 | 19.1 ppb | |
2016-11-07 | 20.9 ppb | |
2016-11-07 | 18.7 ppb | |
2016-11-07 | 12.6 ppb | |
2016-11-07 | 13.2 ppb | |
2016-11-07 | 12.5 ppb | |
2016-11-07 | 11.7 ppb | |
2017-02-07 | 18.2 ppb | |
2017-02-07 | 15.9 ppb | |
2017-02-07 | 28.9 ppb | |
2017-02-07 | 17.0 ppb | |
2017-02-07 | 45.9 ppb | |
2017-02-07 | 15.5 ppb | |
2017-02-07 | 26.4 ppb | |
2017-02-07 | 14.7 ppb | |
2017-02-07 | 16.6 ppb | |
2017-02-07 | 33.0 ppb | |
2017-02-07 | 16.8 ppb | |
2017-02-07 | 25.5 ppb | |
2017-04-11 | ND | |
2017-04-11 | ND | |
2017-04-11 | ND | |
2017-04-11 | ND | |
2017-04-11 | 11.1 ppb | |
2017-04-17 | 9.41 ppb | |
2017-04-17 | 17.8 ppb | |
2017-05-02 | 15.6 ppb | |
2017-05-02 | 15.2 ppb | |
2017-05-02 | 11.9 ppb | |
2017-05-02 | 19.4 ppb | |
2017-05-02 | 20.3 ppb | |
2017-05-02 | 18.2 ppb | |
2017-05-02 | 25.0 ppb | |
2017-05-02 | 15.2 ppb | |
2017-05-02 | 12.7 ppb | |
2017-05-02 | 18.5 ppb | |
2017-05-15 | 53.0 ppb | |
2017-05-15 | 29.2 ppb | |
2017-06-05 | 1.44 ppb | |
2017-06-05 | ND | |
2017-06-05 | ND | |
2017-06-05 | ND | |
2017-06-05 | ND | |
2017-08-07 | 24.4 ppb | |
2017-08-07 | 21.1 ppb | |
2017-08-07 | 21.5 ppb | |
2017-08-07 | 22.4 ppb | |
2017-08-07 | 25.3 ppb | |
2017-08-07 | 21.3 ppb | |
2017-08-07 | 22.6 ppb | |
2017-08-07 | 25.0 ppb | |
2017-08-07 | 24.0 ppb | |
2017-08-07 | 21.1 ppb | |
2017-08-07 | 21.2 ppb | |
2017-08-07 | 23.3 ppb | |
2017-09-19 | ND | |
2017-11-07 | 19.9 ppb | |
2017-11-07 | 38.4 ppb | |
2017-11-07 | 17.9 ppb | |
2017-11-07 | 18.6 ppb | |
2017-11-07 | 16.8 ppb | |
2017-11-07 | 18.4 ppb | |
2017-11-07 | 17.5 ppb | |
2017-11-07 | 19.8 ppb | |
2017-11-07 | 19.8 ppb | |
2017-11-07 | 16.4 ppb | |
2017-11-07 | 18.1 ppb | |
2017-11-07 | 35.3 ppb | |
2018-02-06 | 534089 | 16.9 ppb |
2018-02-06 | 534090 | 11.3 ppb |
2018-02-06 | 534091 | 10.3 ppb |
2018-02-06 | 534092 | 10.3 ppb |
2018-02-06 | 534093 | 14.6 ppb |
2018-02-06 | 534094 | 11.8 ppb |
2018-02-06 | 534095 | 10.5 ppb |
2018-02-06 | 534096 | 10.6 ppb |
2018-02-06 | 534097 | 15.1 ppb |
2018-02-06 | 534098 | 16.8 ppb |
2018-02-06 | 534099 | 17.9 ppb |
2018-02-06 | 534100 | 14.9 ppb |
2018-05-07 | 549814 | 42.3 ppb |
2018-05-07 | 549815 | 29.5 ppb |
2018-05-07 | 549816 | 48.5 ppb |
2018-05-07 | 549817 | 13.4 ppb |
2018-05-07 | 549818 | 31.6 ppb |
2018-05-07 | 549819 | 12.2 ppb |
2018-05-07 | 549820 | 38.5 ppb |
2018-05-07 | 549821 | 37.8 ppb |
2018-05-07 | 549822 | 28.8 ppb |
2018-05-07 | 549823 | 48.6 ppb |
2018-05-07 | 549824 | 40.9 ppb |
2018-05-07 | 549825 | 41.2 ppb |
2018-05-14 | 542539 | 16.2 ppb |
2018-05-14 | 542540 | 25.2 ppb |
2018-08-08 | 567019 | 38.3 ppb |
2018-08-08 | 567020 | 21.5 ppb |
2018-08-08 | 567021 | 24.4 ppb |
2018-08-08 | 567022 | 26.5 ppb |
2018-08-08 | 567023 | 25.2 ppb |
2018-08-08 | 567024 | 29.1 ppb |
2018-08-08 | 567025 | 26.1 ppb |
2018-08-08 | 567026 | 23.6 ppb |
2018-08-08 | 567027 | 24.9 ppb |
2018-08-08 | 567028 | 30.6 ppb |
2018-08-08 | 567029 | 25.0 ppb |
2018-08-08 | 567030 | 24.9 ppb |
2018-11-06 | 583374 | 24.5 ppb |
2018-11-06 | 583375 | 21.7 ppb |
2018-11-06 | 583376 | 25.5 ppb |
2018-11-06 | 583377 | 19.9 ppb |
2018-11-06 | 583378 | 24.0 ppb |
2018-11-06 | 583379 | 19.5 ppb |
2018-11-06 | 583380 | 24.7 ppb |
2018-11-06 | 583381 | 18.9 ppb |
2018-11-06 | 583382 | 25.6 ppb |
2018-11-06 | 583383 | 22.8 ppb |
2018-11-06 | 583384 | 24.0 ppb |
2018-11-06 | 583385 | 25.2 ppb |
2019-02-05 | 595236 | 13.7 ppb |
2019-02-05 | 595237 | 16.5 ppb |
2019-02-05 | 595238 | 18.7 ppb |
2019-02-05 | 595239 | 18.9 ppb |
2019-02-05 | 595240 | 17.3 ppb |
2019-02-05 | 595241 | 19.8 ppb |
2019-02-05 | 595242 | 21.5 ppb |
2019-02-05 | 595243 | 19.2 ppb |
2019-02-05 | 595244 | 19.8 ppb |
2019-02-05 | 595245 | 20.2 ppb |
2019-02-05 | 595246 | 17.4 ppb |
2019-02-05 | 595247 | 21.6 ppb |
2019-04-02 | 604245 | 21.2 ppb |
2019-04-22 | 604810 | 14.9 ppb |
2019-05-07 | 600564 | 18.6 ppb |
2019-05-07 | 600565 | 20.1 ppb |
2019-05-07 | 600566 | 45.4 ppb |
2019-05-07 | 600567 | 37.2 ppb |
2019-05-07 | 600568 | 57.6 ppb |
2019-05-07 | 600569 | 51.7 ppb |
2019-05-07 | 600570 | 55.3 ppb |
2019-05-07 | 600571 | 33.7 ppb |
2019-05-07 | 600572 | 52.6 ppb |
2019-05-07 | 600573 | 56.2 ppb |
2019-05-07 | 600574 | 53.0 ppb |
2019-05-07 | 600575 | 51.8 ppb |
2019-06-10 | 604811 | ND |
2019-08-06 | 622448 | 34.4 ppb |
2019-08-06 | 622449 | 41.5 ppb |
2019-08-06 | 622450 | 43.0 ppb |
2019-08-06 | 622451 | 36.9 ppb |
2019-08-06 | 622452 | 38.7 ppb |
2019-08-06 | 622453 | 36.8 ppb |
2019-08-06 | 622454 | 35.9 ppb |
2019-08-06 | 622455 | 38.5 ppb |
2019-08-06 | 622456 | 30.9 ppb |
2019-08-06 | 622457 | 40.7 ppb |
2019-08-06 | 622458 | 40.9 ppb |
2019-08-06 | 622459 | 36.7 ppb |
2019-11-05 | 644378 | 21.5 ppb |
2019-11-05 | 644379 | 22.0 ppb |
2019-11-05 | 644380 | 26.2 ppb |
2019-11-05 | 644381 | 29.3 ppb |
2019-11-05 | 644382 | 26.1 ppb |
2019-11-05 | 644383 | 29.2 ppb |
2019-11-05 | 644384 | 21.0 ppb |
2019-11-05 | 644385 | 21.2 ppb |
2019-11-05 | 644386 | 35.4 ppb |
2019-11-05 | 644387 | 26.6 ppb |
2019-11-05 | 644388 | 26.0 ppb |
2019-11-05 | 644389 | 34.9 ppb |