Total trihalomethanes (TTHMs)
Dewitt WDS - South
Trihalomethanes are cancer-causing contaminants that form during water treatment with chlorine and other disinfectants. The total trihalomethanes group includes four chemicals: chloroform, bromodichloromethane, dibromochloromethane and bromoform. Read More.
Studies conducted in the U.S. and Europe have found that drinking tap water that carries disinfection byproducts increases the risk of developing bladder cancer. In animal studies, all trihalomethanes cause liver, kidney and intestinal tumors. Some human epidemiological studies also reported an association between disinfection byproducts and an increased risk of problems during pregnancy, including spontaneous miscarriage, cardiovascular defects, neural tube defects and low birth weight.
The health guideline of 0.15 parts per billion, or ppb, for the group of four trihalomethanes, or THM4/TTHM, was defined in a peer-reviewed scientific study by EWG and represents a one-in-one-million lifetime cancer risk level.
Testing results - average by year
Year | Average result | Samples taken | Detections | Range of results |
---|---|---|---|---|
2014 | 44.6 ppb | 8 | 8 | 28.0 ppb - 57.0 ppb |
2015 | 45.3 ppb | 8 | 8 | 28.0 ppb - 55.0 ppb |
2016 | 42.0 ppb | 8 | 8 | 21.0 ppb - 59.0 ppb |
2017 | 55.2 ppb | 6 | 6 | 43.0 ppb - 73.0 ppb |
2018 | 44.8 ppb | 8 | 8 | 32.0 ppb - 55.0 ppb |
2019 | 52.3 ppb | 8 | 8 | 46.0 ppb - 68.0 ppb |
ppb = parts per billion
State and national drinking water standards and health guidelines
EWG Health Guideline 0.15 ppb
The health guideline of 0.15 parts per billion, or ppb, for the group of four trihalomethanes, or THM4/TTHM, was defined in a peer-reviewed scientific study by EWG and represents a one-in-one-million lifetime cancer risk level.
EPA Maximum Contaminant
Level (MCL) 80 ppb
The legal limit for the group of four trihalomethanes, established in 1998, was based on the need for residual disinfectant levels in water served to customers and the cost of treatment. This limit does not fully protect against the risk of cancer due to exposure to trihalomethanes.
ppb = parts per billion
All test results
Date | Lab ID | Result |
---|---|---|
2014-02-13 | 1Q2014 CORONATIO | 43.0 ppb |
2014-02-13 | 1Q2014 JD EDINGE | 28.0 ppb |
2014-05-13 | 2Q2014 CORONATIO | 37.0 ppb |
2014-05-13 | 2Q2014 JD EDINGE | 43.0 ppb |
2014-08-13 | 3Q2014 JD EDINGE | 50.0 ppb |
2014-08-13 | 3Q2014 CORONATIO | 49.0 ppb |
2014-11-13 | 4Q2014 CORONATIO | 57.0 ppb |
2014-11-13 | 4Q2014 JD EDINGE | 50.0 ppb |
2015-02-11 | 1Q2015 CORONATIO | 44.0 ppb |
2015-02-11 | 1Q2015 JD EDINGE | 28.0 ppb |
2015-05-14 | 2Q2015 JD EDINGE | 38.0 ppb |
2015-05-14 | 2Q2015 CORONATIO | 43.0 ppb |
2015-08-13 | 3Q2015 JD EDINGE | 53.0 ppb |
2015-08-13 | 3Q2015 CORONATIO | 47.0 ppb |
2015-11-09 | 4Q2015 CORONATIO | 54.0 ppb |
2015-11-09 | 4Q2015 JD EDINGE | 55.0 ppb |
2016-02-12 | 1Q2016 CORONATIO | 21.0 ppb |
2016-02-12 | 1Q2016 JD EDINGE | 29.0 ppb |
2016-05-17 | 2Q2016 JD EDINGE | 33.0 ppb |
2016-05-17 | 2Q2016 CORONATIO | 41.0 ppb |
2016-08-10 | 3Q2016 CORONATIO | 59.0 ppb |
2016-08-10 | 3Q2016 JD EDINGE | 53.0 ppb |
2016-11-08 | 4Q2016 JD EDINGE | 51.0 ppb |
2016-11-08 | 4Q2016 CORONATIO | 49.0 ppb |
2017-05-10 | 2Q2017 CORONATIO | 45.0 ppb |
2017-05-10 | 2Q2017 JD EDINGE | 53.0 ppb |
2017-08-09 | 3Q2017 CORONATIO | 73.0 ppb |
2017-08-09 | 3Q2017 JD EDINGE | 73.0 ppb |
2017-11-07 | 4Q2017 CORONATIO | 43.0 ppb |
2017-11-07 | 4Q2017 JD EDINGE | 44.0 ppb |
2018-02-15 | 1Q2018 EDINGER D | 33.0 ppb |
2018-02-15 | 1Q2018 CORONATIO | 32.0 ppb |
2018-05-10 | 2Q2018 JD EDINGE | 47.0 ppb |
2018-05-10 | 2Q2018 CORONATIO | 44.0 ppb |
2018-08-16 | 3Q2018 CORONATIO | 54.0 ppb |
2018-08-16 | 3Q2018 JD EDINGE | 55.0 ppb |
2018-11-07 | 4Q2018 JD EDINGE | 48.0 ppb |
2018-11-17 | 4Q2018 CORONATIO | 45.0 ppb |
2019-02-14 | 1Q2019 CORONATIO | 47.0 ppb |
2019-02-14 | 1Q2019 JD EDINGE | 46.0 ppb |
2019-05-10 | 2Q2019 CORONATIO | 46.0 ppb |
2019-05-10 | 2Q2019 JD EDINGE | 52.0 ppb |
2019-08-13 | 3Q2019 CORONATIO | 68.0 ppb |
2019-08-13 | 3Q2019 JD EDINGE | 62.0 ppb |
2019-11-06 | 4Q2019 CORONATIO | 49.0 ppb |
2019-11-06 | 4Q2019 JD EDINGE | 48.0 ppb |