Chloroform
La Crosse Waterworks
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 |
|---|---|---|---|---|
| 2014 | 1.28 ppb | 19 | 13 | ND - 11.2 ppb |
| 2015 | 1.15 ppb | 18 | 12 | ND - 10.1 ppb |
| 2016 | 0.951 ppb | 16 | 13 | ND - 5.82 ppb |
| 2017 | 0.766 ppb | 22 | 6 | ND - 9.28 ppb |
| 2018 | 0.612 ppb | 16 | 2 | ND - 5.53 ppb |
| 2019 | 0.391 ppb | 18 | 2 | ND - 3.87 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 |
|---|---|---|
| 2014-02-25 | 4020695-01 | 0.403 ppb |
| 2014-03-06 | 4030179-02 | ND |
| 2014-03-10 | 4030238-02 | ND |
| 2014-03-10 | 4030238-01 | 0.0920 ppb |
| 2014-04-22 | 4040806-16 | 0.581 ppb |
| 2014-06-11 | 4060407-02 | ND |
| 2014-06-11 | 4060407-04 | ND |
| 2014-06-11 | 4060407-01 | 0.404 ppb |
| 2014-06-11 | 4060407-03 | 0.654 ppb |
| 2014-06-16 | 4060519-04 | ND |
| 2014-06-16 | 4060519-02 | 0.486 ppb |
| 2014-06-24 | 4060840-01 | ND |
| 2014-08-11 | 4080309-01 | 0.430 ppb |
| 2014-08-13 | 4080455-02 | 0.175 ppb |
| 2014-08-13 | 4080455-03 | 0.597 ppb |
| 2014-08-13 | 4080455-05 | 5.83 ppb |
| 2014-08-13 | 4080455-04 | 11.2 ppb |
| 2014-10-08 | 4100322-07 | 0.155 ppb |
| 2014-12-30 | 4120949-01 | 3.34 ppb |
| 2015-02-11 | 5020318-04 | ND |
| 2015-02-11 | 5020318-02 | 0.104 ppb |
| 2015-02-11 | 5020318-03 | 0.358 ppb |
| 2015-03-09 | 5030238-01 | ND |
| 2015-03-30 | 5030975-01 | ND |
| 2015-04-01 | 5040003-01 | ND |
| 2015-05-06 | 5050178-03 | 0.684 ppb |
| 2015-05-06 | 5050178-04 | 0.928 ppb |
| 2015-05-06 | 5050178-02 | 1.76 ppb |
| 2015-06-16 | 5060564-04 | ND |
| 2015-08-13 | 5080540-04 | 0.276 ppb |
| 2015-08-13 | 5080540-02 | 0.343 ppb |
| 2015-08-13 | 5080540-03 | 0.617 ppb |
| 2015-08-13 | 5080540-05 | 4.92 ppb |
| 2015-08-13 | 5080540-06 | 10.1 ppb |
| 2015-10-14 | 5100472-04 | ND |
| 2015-10-14 | 5100472-02 | 0.202 ppb |
| 2015-10-14 | 5100472-03 | 0.341 ppb |
| 2016-03-10 | 6030418-05 | ND |
| 2016-03-10 | 6030418-06 | 0.169 ppb |
| 2016-03-10 | 6030418-02 | 0.201 ppb |
| 2016-03-10 | 6030418-01 | 0.345 ppb |
| 2016-03-10 | 6030418-03 | 0.418 ppb |
| 2016-04-14 | 6040500-01 | 0.723 ppb |
| 2016-05-18 | 6050700-05 | ND |
| 2016-05-18 | 6050700-03 | 0.337 ppb |
| 2016-05-18 | 6050700-04 | 0.496 ppb |
| 2016-08-10 | 6080456-07 | ND |
| 2016-08-10 | 6080456-03 | 0.499 ppb |
| 2016-08-10 | 6080457-01 | 4.10 ppb |
| 2016-08-10 | 6080457-02 | 5.82 ppb |
| 2016-11-03 | 6110193-08 | 0.640 ppb |
| 2016-11-03 | 6110193-07 | 0.651 ppb |
| 2016-11-03 | 6110193-03 | 0.814 ppb |
| 2017-03-08 | 17C0300-01 | ND |
| 2017-03-15 | 17C0533-01 | ND |
| 2017-03-16 | 17C0605-01 | ND |
| 2017-06-14 | 17F0575-08 | ND |
| 2017-06-14 | 17F0575-02 | ND |
| 2017-06-14 | 17F0575-07 | ND |
| 2017-06-14 | 17F0575-05 | ND |
| 2017-06-14 | 17F0575-06 | ND |
| 2017-06-14 | 17F0575-03 | 0.266 ppb |
| 2017-06-14 | 17F0575-04 | 0.441 ppb |
| 2017-06-15 | 17F0598-01 | ND |
| 2017-06-21 | 17F0857-01 | ND |
| 2017-06-21 | 17F0857-03 | ND |
| 2017-08-09 | 17H0448-02 | ND |
| 2017-08-09 | 17H0448-05 | ND |
| 2017-08-09 | 17H0448-04 | 0.305 ppb |
| 2017-08-09 | 17H0448-03 | 0.320 ppb |
| 2017-08-09 | 17H0448-08 | 6.23 ppb |
| 2017-08-09 | 17H0448-07 | 9.28 ppb |
| 2017-10-23 | 17J0751-02 | ND |
| 2017-10-23 | 17J0751-03 | ND |
| 2017-10-23 | 17J0751-04 | ND |
| 2018-02-28 | 18B0840-03 | ND |
| 2018-02-28 | 18B0840-04 | ND |
| 2018-02-28 | 18B0840-06 | ND |
| 2018-05-02 | 18E0103-03 | ND |
| 2018-05-02 | 18E0103-04 | ND |
| 2018-05-02 | 18E0103-05 | ND |
| 2018-05-02 | 18E0103-06 | ND |
| 2018-05-03 | 18E0132-02 | ND |
| 2018-08-01 | 18H0053-02 | ND |
| 2018-08-01 | 18H0053-03 | ND |
| 2018-08-01 | 18H0053-04 | ND |
| 2018-08-01 | 18H0053-07 | 4.26 ppb |
| 2018-08-01 | 18H0053-06 | 5.53 ppb |
| 2018-10-01 | 18J0009-02 | ND |
| 2018-10-01 | 18J0009-03 | ND |
| 2018-10-01 | 18J0009-04 | ND |
| 2019-03-04 | 19C0052-01 | ND |
| 2019-03-04 | 19C0052-03 | ND |
| 2019-03-05 | 19C0107-01 | ND |
| 2019-03-18 | 19C0513-02 | ND |
| 2019-06-06 | 19F0212-01 | ND |
| 2019-06-06 | 19F0212-02 | ND |
| 2019-06-06 | 19F0212-03 | ND |
| 2019-06-06 | 19F0212-05 | ND |
| 2019-07-22 | 19G0736-01 | ND |
| 2019-07-22 | 19G0736-03 | ND |
| 2019-07-22 | 19G0736-04 | ND |
| 2019-07-22 | 19G0736-06 | ND |
| 2019-07-22 | 19G0736-08 | 3.17 ppb |
| 2019-07-22 | 19G0736-07 | 3.87 ppb |
| 2019-10-02 | 19J0142-01 | ND |
| 2019-10-02 | 19J0142-02 | ND |
| 2019-10-02 | 19J0142-03 | ND |
| 2019-10-02 | 19J0142-04 | ND |