Know Your Environment. Protect Your Health.

Total trihalomethanes (TTHMs)

Remlap-Pine Mountain Water Authority

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.

 

48

Samples

0

Samples exceeding legal limit (MCL)

37

Samples exceeding
health guidelines

Testing results - average by year

 
YearAverage resultSamples takenDetectionsRange of results
201837.9 ppb8813.1 ppb - 79.7 ppb
20194.89 ppb87ND - 8.50 ppb
20202.15 ppb85ND - 5.00 ppb
20211.23 ppb85ND - 3.00 ppb
202213.6 ppb86ND - 43.0 ppb
20231.13 ppb86ND - 3.00 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
2018-02-16180216053-213.1 ppb
2018-02-16180216053-114.4 ppb
2018-05-18180518066-225.8 ppb
2018-05-18180518066-118.7 ppb
2018-08-1718080559-00137.5 ppb
2018-08-1718080559-00235.1 ppb
2018-11-1518110431-00178.7 ppb
2018-11-1518110431-00279.7 ppb
2019-02-1419020552-0018.50 ppb
2019-02-1419020552-0025.00 ppb
2019-05-1619050551-0018.20 ppb
2019-05-1619050551-0028.00 ppb
2019-08-1620117530002_DBP22.60 ppb
2019-08-1620117530001_DBP25.70 ppb
2019-11-1420130720001_DBP21.10 ppb
2019-11-1420130720002_DBP2ND
2020-02-1320142709001_DBP2ND
2020-02-1320142709002_DBP2ND
2020-05-1420154730001_DBP21.50 ppb
2020-05-1420154730002_DBP2ND
2020-08-1320167401001_DBP25.00 ppb
2020-08-1320167401002_DBP24.10 ppb
2020-11-1220179959001_DBP23.80 ppb
2020-11-1220179959002_DBP22.80 ppb
2021-02-1135612898001_DBP2ND
2021-02-1135612898002_DBP2ND
2021-05-1335633429001_DBP21.10 ppb
2021-05-1335633429002_DBP21.10 ppb
2021-08-12356557510013.00 ppb
2021-08-12356557510023.00 ppb
2021-11-1235677483001_DBP21.60 ppb
2021-11-1235677483002_DBP2ND
2022-02-1835698127001_DBP2ND
2022-02-1835698127002_DBP2ND
2022-05-1235717559001A_DBP212.0 ppb
2022-05-1235717559002A_DBP21.40 ppb
2022-08-1235739462001_DBP243.0 ppb
2022-08-1235739462002_DBP240.0 ppb
2022-11-1735761011001_DBP24.00 ppb
2022-11-1735761011002_DBP28.70 ppb
2023-02-1635780484001_DBP2ND
2023-02-1635780484002_DBP2ND
2023-05-1135799398001_DBP21.10 ppb
2023-05-1135799398002_DBP21.10 ppb
2023-08-1835821842001_DBP23.00 ppb
2023-08-1835821842002_DBP21.40 ppb
2023-11-3035844936001_DBP21.10 ppb
2023-11-3035844936002_DBP21.30 ppb