Know Your Environment. Protect Your Health.

Total trihalomethanes (TTHMs)

City of Crosbyton

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.

 

24

Samples

0

Samples exceeding legal limit (MCL)

2

Samples exceeding
health guidelines

Testing results - average by year

 
YearAverage resultSamples takenDetectionsRange of results
201813.2 ppb42ND - 47.9 ppb
2019ND40ND
2020ND40ND
2021ND40ND
2022ND40ND
2023ND40ND

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
2018-02-06Q1804611008ND
2018-04-24Q1816511001ND
2018-07-17Q182822900147.9 ppb
2018-11-14Q18462350024.98 ppb
2019-02-12Q1906200005ND
2019-05-01Q1917586002ND
2019-08-06Q1951421002ND
2019-10-09Q1972065002ND
2020-03-09Q2008466004ND
2020-05-19Q2019884005ND
2020-09-15Q2036515002ND
2020-11-16Q2044958001ND
2021-03-04Q2105770001ND
2021-04-29Q2110926010ND
2021-08-11Q2121423002ND
2021-12-02Q2133344002ND
2022-03-14Q2208564005ND
2022-06-02Q2215629002ND
2022-09-06Q2226329002ND
2022-12-08Q2236957002ND
2023-02-09Q2305227006ND
2023-04-27Q2315858001ND
2023-08-17Q2334683002ND
2023-10-11Q2343429002ND