Know Your Environment. Protect Your Health.

Total trihalomethanes (TTHMs)

Lido-point Lookout Water District

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.

 

50

Samples

0

Samples exceeding legal limit (MCL)

3

Samples exceeding
health guidelines

Testing results - average by year

 
YearAverage resultSamples takenDetectionsRange of results
2018ND60ND
2019ND90ND
20200.256 ppb91ND - 2.30 ppb
20210.0562 ppb131ND - 0.730 ppb
2022ND110ND
20230.375 ppb21ND - 0.750 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
2018-01-117040219009-POCND
2018-01-117040219008-POCND
2018-07-207058920005-POCND
2018-07-207058920006-POCND
2018-10-117067692005ND
2018-10-117067692006ND
2019-01-237077393004ND
2019-01-237077393003ND
2019-04-187086468009ND
2019-04-187086468008ND
2019-07-097096748006ND
2019-07-097096748007ND
2019-10-1770108828008ND
2019-10-1770108828009ND
2019-10-2497349ND
2020-01-1470118357006ND
2020-01-1470118357005ND
2020-04-2370129041002ND
2020-04-2370129041001ND
2020-09-014714786ND
2020-09-30701477530012.30 ppb
2020-10-0870148838007ND
2020-10-0870148838006ND
2020-10-0870148838005ND
2021-01-1570159661006ND
2021-01-1570159661005ND
2021-01-1570159661007ND
2021-06-03701755440050.730 ppb
2021-06-0870176052006ND
2021-06-0870176052007ND
2021-07-1570180617001ND
2021-07-1570180617002ND
2021-07-1570180617003ND
2021-09-07810-1236-1ND
2021-10-2770192508002ND
2021-10-2770192508004ND
2021-10-2770192508001ND
2022-01-2570201886007ND
2022-01-2570201886008ND
2022-01-2570201886006ND
2022-06-1470218200001ND
2022-06-1470218200002ND
2022-07-2170223046005ND
2022-07-2170223046006ND
2022-08-1670226006003ND
2022-10-0670232553002ND
2022-10-0670232553004ND
2022-10-0670232553001ND
2023-09-07810-76999-10.750 ppb
2023-12-2070281775004ND