Know Your Environment. Protect Your Health.

Total trihalomethanes (TTHMs)

Woodridge Village

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.

 

23

Samples

3

Samples exceeding legal limit (MCL)

23

Samples exceeding
health guidelines

Testing results - average by year

 
YearAverage resultSamples takenDetectionsRange of results
201861.5 ppb4433.0 ppb - 95.7 ppb
201942.8 ppb2231.9 ppb - 53.7 ppb
202035.4 ppb5523.9 ppb - 42.0 ppb
202169.1 ppb4432.0 ppb - 111.0 ppb
202244.4 ppb4420.6 ppb - 65.0 ppb
202354.1 ppb4420.3 ppb - 86.0 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
2018-03-01DBP J8C029143.4 ppb
2018-05-10DBP J8E0880-0195.7 ppb
2018-07-19DBP J8G1736-0173.9 ppb
2018-11-15DBP J8K0981-01,233.0 ppb
2019-02-28DBP J9B1399-0131.9 ppb
2019-07-25DBP J9G1503-0153.7 ppb
2020-02-05DBP S00002331937.8 ppb
2020-05-04TTHM S00002650123.9 ppb
2020-07-31DBP9 S00003228536.6 ppb
2020-08-03DBP9 S00003018736.6 ppb
2020-11-03DBP S030182,9542.0 ppb
2021-03-24DBP 369667-0132.0 ppb
2021-05-19DBP 37129958.0 ppb
2021-08-10DBP S062168,57417111.0 ppb
2021-11-03DBP S068292,375.5 ppb
2022-02-08DBP S07481420.6 ppb
2022-05-10DBP S074282,1365.0 ppb
2022-08-02DBP S000074783,91057.9 ppb
2022-11-09DBP S0103915,3134.1 ppb
2023-02-08DBP S0137412,0020.3 ppb
2023-05-02DBP SO137398, 41364.0 ppb
2023-08-10DBP S0137399,40786.0 ppb
2023-11-15DBP S00016618346.0 ppb