Know Your Environment. Protect Your Health.

Total trihalomethanes (TTHMs)

CTWC - Naugatuck Region-Central System

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.

 

96

Samples

0

Samples exceeding legal limit (MCL)

96

Samples exceeding
health guidelines

Testing results - average by year

 
YearAverage resultSamples takenDetectionsRange of results
201839.3 ppb161620.6 ppb - 51.5 ppb
201935.5 ppb161612.7 ppb - 48.7 ppb
202030.6 ppb16169.20 ppb - 60.9 ppb
202129.0 ppb16167.00 ppb - 46.3 ppb
202231.6 ppb161613.4 ppb - 55.5 ppb
202327.6 ppb161612.0 ppb - 48.5 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
2018-02-14BZ89698TTHM46.1 ppb
2018-02-14BZ89699TTHM44.6 ppb
2018-02-14BZ89700TTHM51.5 ppb
2018-02-14BZ89697TTHM31.4 ppb
2018-05-21CA50437TTHM34.8 ppb
2018-05-21CA50438TTHM20.6 ppb
2018-05-21CA50439TTHM38.0 ppb
2018-05-21CA50440TTHM36.6 ppb
2018-08-20CB1493928.5 ppb
2018-08-20CB1494042.4 ppb
2018-08-20CB1494141.5 ppb
2018-08-20CB1494242.3 ppb
2018-11-20DBP 20051350446.8 ppb
2018-11-20DBP 20051353449.4 ppb
2018-11-20DBP 20051350629.2 ppb
2018-11-20DBP 20051350245.9 ppb
2019-02-20DBP 20052244738.4 ppb
2019-02-20DBP 20052244834.4 ppb
2019-02-20DBP 20052244938.8 ppb
2019-02-20DBP 20052245024.1 ppb
2019-05-21DBP 20053325735.2 ppb
2019-05-21DBP 20053325828.7 ppb
2019-05-21DBP 20053325936.5 ppb
2019-05-21DBP 20053326012.7 ppb
2019-08-20DBP 20054589143.9 ppb
2019-08-20DBP 20054589323.1 ppb
2019-08-20DBP 20054589240.7 ppb
2019-08-20DBP 20054589045.9 ppb
2019-11-19DBP 20055740548.0 ppb
2019-11-19DBP 20055740647.4 ppb
2019-11-19DBP 20055740721.9 ppb
2019-11-19DBP 20055740448.7 ppb
2020-02-19DBP 20056688032.5 ppb
2020-02-19DBP 20056688129.0 ppb
2020-02-19DBP 20056688236.9 ppb
2020-02-19DBP 20056688313.8 ppb
2020-05-05DBP 20057462916.2 ppb
2020-05-05DBP 20057463040.2 ppb
2020-05-05DBP 20057462825.5 ppb
2020-05-05DBP 20057462722.6 ppb
2020-08-14DBP 20058671760.9 ppb
2020-08-14DBP 20058672144.9 ppb
2020-08-14DBP 20058672227.6 ppb
2020-08-14DBP 20058672354.7 ppb
2020-11-17DBP 20059852921.7 ppb
2020-11-17DBP 20059853020.3 ppb
2020-11-17DBP 2005985319.20 ppb
2020-11-17DBP 20059853233.7 ppb
2021-02-17DBP 20060709122.7 ppb
2021-02-17DBP 20060708813.8 ppb
2021-02-17DBP 20060708913.0 ppb
2021-02-17DBP 2006070907.00 ppb
2021-05-21DBP 20061817426.7 ppb
2021-05-21DBP 20061817518.1 ppb
2021-05-21DBP 20061817641.2 ppb
2021-05-21DBP 20061817335.7 ppb
2021-08-12DBP 20062891938.1 ppb
2021-08-12DBP 20062892036.6 ppb
2021-08-12DBP 20062892120.8 ppb
2021-08-12DBP 20062892246.3 ppb
2021-11-02D300094268 30009427643.0 ppb
2021-11-02D300094267 30009427421.7 ppb
2021-11-02D300094266 30009427239.4 ppb
2021-11-02D300094265 30009427040.2 ppb
2022-02-22CK7305830.5 ppb
2022-02-22CK7305925.2 ppb
2022-02-22CK7306037.6 ppb
2022-02-22CK7306119.9 ppb
2022-05-20CL3607326.8 ppb
2022-05-20CL3607426.7 ppb
2022-05-20CL3607538.3 ppb
2022-05-20CL3607620.1 ppb
2022-08-03CL9638332.9 ppb
2022-08-03CL9638148.4 ppb
2022-08-03CL9638055.5 ppb
2022-08-03CL9638254.6 ppb
2022-11-04CM7928527.9 ppb
2022-11-04CM7928619.8 ppb
2022-11-04CM7928727.4 ppb
2022-11-04CM7928813.4 ppb
2023-02-09CN4144118.2 ppb
2023-02-09CN4144214.8 ppb
2023-02-09CN4144323.5 ppb
2023-02-09CN4144412.0 ppb
2023-05-08CO0164521.6 ppb
2023-05-08CO0164714.6 ppb
2023-05-08CO0164629.6 ppb
2023-05-08CO0164424.8 ppb
2023-08-04CO6817048.5 ppb
2023-08-04CO6817136.4 ppb
2023-08-04CO6817240.9 ppb
2023-08-04CO6817323.7 ppb
2023-11-03CP4146339.3 ppb
2023-11-03CP4146430.9 ppb
2023-11-03CP4146538.5 ppb
2023-11-03CP4146624.3 ppb