Know Your Environment. Protect Your Health.

Total trihalomethanes (TTHMs)

Bellflower Municipal Water 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.

 

46

Samples

0

Samples exceeding legal limit (MCL)

22

Samples exceeding
health guidelines

Testing results - average by year

 
YearAverage resultSamples takenDetectionsRange of results
20181.74 ppb86ND - 3.60 ppb
20190.863 ppb83ND - 3.50 ppb
20200.690 ppb83ND - 2.40 ppb
20210.867 ppb106ND - 2.80 ppb
2022ND60ND
20230.883 ppb64ND - 1.40 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
2018-01-08CA1910018_DST_801-2018010808552.90 ppb
2018-01-08CA1910018_DST_800-201801080753ND
2018-04-10CA1910018_DST_800-201804100732ND
2018-04-10CA1910018_DST_801-2018041008141.50 ppb
2018-07-10CA1910018_DST_800-2018071009451.000 ppb
2018-07-10CA1910018_DST_801-2018071009562.60 ppb
2018-10-09CA1910018_DST_800-2018100909442.30 ppb
2018-10-09CA1910018_DST_801-2018100910003.60 ppb
2019-01-08CA1910018_DST_800-201901081005ND
2019-01-08CA1910018_DST_801-2019010810171.10 ppb
2019-04-09CA1910018_DST_800-2019040907172.30 ppb
2019-04-09CA1910018_DST_801-2019040908273.50 ppb
2019-07-09CA1910018_DST_800-201907090930ND
2019-07-09CA1910018_DST_801-201907090957ND
2019-10-08CA1910018_DST_800-201910080940ND
2019-10-08CA1910018_DST_801-201910081010ND
2020-01-14CA1910018_DST_800-202001141010ND
2020-01-14CA1910018_DST_801-202001141050ND
2020-04-14CA1910018_DST_800-202004140657ND
2020-04-14CA1910018_DST_801-202004140650ND
2020-07-14CA1910018_DST_801-2020071408452.40 ppb
2020-07-14CA1910018_DST_800-202007140915ND
2020-10-13CA1910018_DST_800-2020101310300.720 ppb
2020-10-13CA1910018_DST_801-2020101310452.40 ppb
2021-01-12CA1910018_DST_801-2021011207202.80 ppb
2021-01-12CA1910018_DST_800-2021011207000.560 ppb
2021-04-13CA1910018_DST_800-2021041308500.710 ppb
2021-04-13CA1910018_DST_801-2021041309151.40 ppb
2021-07-13CA1910018_DST_800-2021071310401.000 ppb
2021-07-13CA1910018_DST_801-2021071311002.20 ppb
2021-09-21CA1910018_DST_800-202109211030ND
2021-09-21CA1910018_DST_801-202109211100ND
2021-10-12CA1910018_DST_801-202110120855ND
2021-10-12CA1910018_DST_800-202110120830ND
2022-01-11CA1910018_DST_801-202201111100ND
2022-01-11CA1910018_DST_800-202201111040ND
2022-04-12CA1910018_DST_801-202204121445ND
2022-04-12CA1910018_DST_800-202204121505ND
2022-07-12CA1910018_DST_800-202207121100ND
2022-07-12CA1910018_DST_801-202207121130ND
2023-04-18CA1910018_DST_800-202304181244ND
2023-04-18CA1910018_DST_801-2023041813021.30 ppb
2023-07-11CA1910018_DST_800-202307111245ND
2023-07-11CA1910018_DST_801-2023071112251.40 ppb
2023-10-16CA1910018_DST_800-2023101608101.20 ppb
2023-10-16CA1910018_DST_801-2023101608321.40 ppb