Know Your Environment. Protect Your Health.

Total trihalomethanes (TTHMs)

Villages of Bocage- Madisonville

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.

Click here to read more about disinfection byproducts.

 

64

Samples

0

Samples exceeding legal limit (MCL)

57

Samples exceeding
health guidelines

Testing results - average by year

 
YearAverage resultSamples takenDetectionsRange of results
20180.820 ppb1614ND - 1.40 ppb
20190.701 ppb1614ND - 0.910 ppb
20200.930 ppb880.610 ppb - 1.24 ppb
20210.501 ppb86ND - 0.820 ppb
20220.814 ppb880.450 ppb - 1.19 ppb
20238.37 ppb87ND - 62.0 ppb

ppb = parts per billion

State, National, and Health Guidelines for Drinking Water

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
2018-02-02353718970011.20 ppb
2018-02-02353718970021.40 ppb
2018-02-02353718970021.40 ppb
2018-02-02353718970011.20 ppb
2018-05-03353903220020.620 ppb
2018-05-03353903220010.800 ppb
2018-05-03353903220020.620 ppb
2018-05-03353903220010.800 ppb
2018-08-01354082730011.000 ppb
2018-08-0135408273002ND
2018-08-01354082730011.000 ppb
2018-08-0135408273002ND
2018-11-15354322770010.640 ppb
2018-11-15354322770010.640 ppb
2018-11-15354322770020.900 ppb
2018-11-15354322770020.900 ppb
2019-02-21354500290010.760 ppb
2019-02-21354500290020.720 ppb
2019-02-21354500290010.760 ppb
2019-02-21354500290020.720 ppb
2019-05-08354682940010.690 ppb
2019-05-0835468294002ND
2019-05-08354682940010.690 ppb
2019-05-0835468294002ND
2019-08-07354884540020.840 ppb
2019-08-07354884540010.840 ppb
2019-08-07354884540010.840 ppb
2019-08-07354884540020.840 ppb
2019-11-15355128710010.910 ppb
2019-11-15355128710020.850 ppb
2019-11-15355128710020.850 ppb
2019-11-15355128710010.910 ppb
2020-02-07355295090020.890 ppb
2020-02-07355295090010.880 ppb
2020-05-08355488290010.610 ppb
2020-05-08355488290020.680 ppb
2020-08-13355707040010.830 ppb
2020-08-13355707040021.24 ppb
2020-11-06355905200011.13 ppb
2020-11-06355905200021.18 ppb
2021-02-05356100090010.660 ppb
2021-02-05356100090020.730 ppb
2021-05-0735631657001ND
2021-05-07356316570020.400 ppb
2021-08-06356537870010.820 ppb
2021-08-06356537870020.810 ppb
2021-11-05356763100010.590 ppb
2021-11-0535676310002ND
2022-02-11356965850020.450 ppb
2022-02-11356965850010.490 ppb
2022-05-06357159290020.780 ppb
2022-05-06357159290010.820 ppb
2022-08-03357370010090.790 ppb
2022-08-03357370010101.16 ppb
2022-11-04357581850011.19 ppb
2022-11-04357581850020.830 ppb
2023-02-03357769780010.570 ppb
2023-02-03357769780021.05 ppb
2023-05-05357977800010.820 ppb
2023-05-05357977800021.29 ppb
2023-08-04358183880010.640 ppb
2023-08-04358183880020.570 ppb
2023-11-0335839347001ND
2023-11-033583934700262.0 ppb