Know Your Environment. Protect Your Health.

Total trihalomethanes (TTHMs)

Lake Shreve Estates 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.

 

68

Samples

17

Samples exceeding legal limit (MCL)

48

Samples exceeding
health guidelines

Testing results - average by year

 
YearAverage resultSamples takenDetectionsRange of results
201813.1 ppb168ND - 69.7 ppb
201980.2 ppb2016ND - 224.0 ppb
20200.221 ppb85ND - 0.380 ppb
2021137.9 ppb8812.3 ppb - 221.0 ppb
202241.2 ppb86ND - 145.0 ppb
202328.7 ppb85ND - 219.0 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
2018-02-1635375107002ND
2018-02-1635375107001ND
2018-02-1635375107002ND
2018-02-1635375107001ND
2018-05-1035392005001ND
2018-05-1035392005002ND
2018-05-1035392005002ND
2018-05-1035392005001ND
2018-08-03354086750011.80 ppb
2018-08-03354086750020.800 ppb
2018-08-03354086750020.800 ppb
2018-08-03354086750011.80 ppb
2018-11-153543219500132.2 ppb
2018-11-153543219500269.7 ppb
2018-11-153543219500132.2 ppb
2018-11-153543219500269.7 ppb
2019-02-2635450785002165.0 ppb
2019-02-2635450785001165.0 ppb
2019-02-2635450785002165.0 ppb
2019-02-2635450785001165.0 ppb
2019-05-1035468313001224.0 ppb
2019-05-1035468313002218.0 ppb
2019-05-1035468313002218.0 ppb
2019-05-1035468313001224.0 ppb
2019-08-01354871870026.70 ppb
2019-08-01354871870026.70 ppb
2019-08-013548718700120.2 ppb
2019-08-013548718700120.2 ppb
2019-08-1535491152002ND
2019-08-15354911520012.90 ppb
2019-08-15354911520012.90 ppb
2019-08-1535491152002ND
2019-11-21355146070020.450 ppb
2019-11-2135514607001ND
2019-11-2135514607001ND
2019-11-21355146070020.450 ppb
2020-02-14355311830010.370 ppb
2020-02-14355311830020.340 ppb
2020-05-22355520610010.350 ppb
2020-05-22355520610020.330 ppb
2020-08-1435570960001ND
2020-08-1435570960002ND
2020-11-30355954060010.380 ppb
2020-11-3035595406002ND
2021-02-2235615351001157.0 ppb
2021-02-2235615351002114.0 ppb
2021-05-0735633214001172.0 ppb
2021-05-0735633214002213.0 ppb
2021-08-273565928600213.5 ppb
2021-08-273565928600112.3 ppb
2021-11-1035676804002221.0 ppb
2021-11-1035676804001200.0 ppb
2022-02-1735699343001142.0 ppb
2022-02-1735699343002145.0 ppb
2022-05-2335721022001ND
2022-05-23357210220021.80 ppb
2022-08-1935741491002ND
2022-08-19357414910010.420 ppb
2022-11-073575979600220.2 ppb
2022-11-073575979600119.8 ppb
2023-02-15357806750014.00 ppb
2023-02-15357806750024.20 ppb
2023-05-25358026180011.20 ppb
2023-05-25358026180020.930 ppb
2023-08-2935824654001ND
2023-08-2935824654002ND
2023-11-0935840812001ND
2023-11-0935840812002219.0 ppb