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EWG's Tap Water Database — 2021 UPDATE

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Total trihalomethanes (TTHMs)

Jackson

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.

MORE ABOUT THIS CONTAMINANT

 

138

Samples

0

Samples exceeding legal limit (MCL)

125

Samples exceeding
health guidelines

Testing results - average by year

 
YearAverage resultSamples takenDetectionsRange of results
2013N/A00N/A
201430.7 ppb2723ND - 65.0 ppb
2015N/A00N/A
201639.2 ppb161629.2 ppb - 50.7 ppb
201744.0 ppb171724.0 ppb - 44.0 ppb
201839.9 ppb3733ND - 68.2 ppb
201930.3 ppb4136ND - 54.0 ppb

ppb = parts per billion

State and national drinking water standards and health guidelines

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
2014-02-19LLF0982822.0 ppb
2014-02-19LLF0982922.0 ppb
2014-03-11LLF11545ND
2014-03-11LLF1154622.0 ppb
2014-03-11LLF1154130.6 ppb
2014-03-11LLF1154229.8 ppb
2014-03-11LLF1154029.6 ppb
2014-03-11LLF1154327.1 ppb
2014-05-07LLF1726824.0 ppb
2014-05-07LLF1726923.0 ppb
2014-06-11LLF22276ND
2014-06-11LLF2227245.0 ppb
2014-06-11LLF2227455.0 ppb
2014-06-11LLF2227551.0 ppb
2014-06-11LLF2227365.0 ppb
2014-08-06LLF3129721.0 ppb
2014-09-03LLF3618038.5 ppb
2014-09-03LLF3617947.3 ppb
2014-09-03LLF36182ND
2014-09-03LLF3618148.5 ppb
2014-09-03LLF3617846.2 ppb
2014-11-05LLF4554827.0 ppb
2014-12-10LLF4919340.0 ppb
2014-12-10LLF4919138.0 ppb
2014-12-10LLF4919441.0 ppb
2014-12-10LLF4919235.0 ppb
2014-12-10LLF49195ND
2016-03-1639.8 ppb
2016-03-1638.4 ppb
2016-03-1629.2 ppb
2016-03-1646.1 ppb
2016-06-1536.7 ppb
2016-06-1535.9 ppb
2016-06-1532.8 ppb
2016-06-1546.3 ppb
2016-09-2143.9 ppb
2016-09-2147.7 ppb
2016-09-2139.6 ppb
2016-09-2150.7 ppb
2016-12-0735.2 ppb
2016-12-0732.2 ppb
2016-12-0732.8 ppb
2016-12-0740.4 ppb
2017-03-0837.0 ppb
2017-03-0841.5 ppb
2017-03-0841.0 ppb
2017-03-0841.8 ppb
2017-06-0144.0 ppb*
2017-06-1446.3 ppb
2017-06-1443.0 ppb
2017-06-1452.7 ppb
2017-06-1458.2 ppb
2017-09-1339.9 ppb
2017-09-1355.8 ppb
2017-09-1346.8 ppb
2017-09-1363.5 ppb
2017-12-1339.1 ppb
2017-12-1342.0 ppb
2017-12-1335.6 ppb
2017-12-1341.9 ppb
2018-02-14LLH6574528.0 ppb
2018-03-14LLH70809ND
2018-03-14LLH7080551.3 ppb
2018-03-14LLH7080749.0 ppb
2018-03-14LLH7080656.7 ppb
2018-03-14LLH7080443.2 ppb
2018-03-1451.3 ppb
2018-03-1456.7 ppb
2018-03-1443.2 ppb
2018-03-1449.0 ppb
2018-05-16LLH8098832.0 ppb
2018-06-05LLH8409149.7 ppb
2018-06-05LLH8409454.0 ppb
2018-06-05LLH8409251.0 ppb
2018-06-05LLH8409357.1 ppb
2018-06-05LLH84095ND
2018-06-0551.0 ppb
2018-06-0557.1 ppb
2018-06-0549.7 ppb
2018-06-0554.0 ppb
2018-08-09LLH9803427.0 ppb
2018-08-29LLI022942.50 ppb
2018-08-29LLI0229268.2 ppb
2018-08-29LLI0229061.4 ppb
2018-08-29LLI0229158.8 ppb
2018-08-29LLI0229359.7 ppb
2018-08-29LLI02295ND
2018-11-15LLI1568720.0 ppb
2018-12-18LLI1986437.5 ppb
2018-12-18LLI1986638.0 ppb
2018-12-18LLI1986332.7 ppb
2018-12-18LLI1986539.2 ppb
2018-12-18LLI19867ND
2018-12-1837.5 ppb
2018-12-1839.2 ppb
2018-12-1832.7 ppb
2018-12-1838.0 ppb
2019-02-12LLI253655.80 ppb
2019-03-12LLI2900828.3 ppb
2019-03-12LLI2900930.9 ppb
2019-03-12LLI29006ND
2019-03-12LLI2901024.8 ppb
2019-03-12LLI2901121.5 ppb
2019-03-1228.3 ppb
2019-03-1230.9 ppb
2019-03-1221.5 ppb
2019-03-1224.8 ppb
2019-05-14LLI3790625.0 ppb
2019-06-25LLI45876ND
2019-06-25LLI4587541.4 ppb
2019-06-25LLI4587234.4 ppb
2019-06-25LLI4587438.5 ppb
2019-06-25LLI4587346.6 ppb
2019-06-2538.5 ppb
2019-06-2541.4 ppb
2019-06-2534.4 ppb
2019-06-2546.6 ppb
2019-08-14LLI5629021.0 ppb
2019-09-04LLI61301ND
2019-09-04LLI6129754.0 ppb
2019-09-04LLI6130053.6 ppb
2019-09-04LLI6129942.4 ppb
2019-09-04LLI6129843.5 ppb
2019-09-0443.5 ppb
2019-09-0453.6 ppb
2019-09-0442.4 ppb
2019-09-0454.0 ppb
2019-10-25LLI72733ND
2019-11-20LLI7820521.0 ppb
2019-12-10LLI8254930.3 ppb
2019-12-10LLI8255032.5 ppb
2019-12-10LLI8254727.8 ppb
2019-12-10LLI8254834.5 ppb
2019-12-10LLI82551ND
2019-12-1030.3 ppb
2019-12-1034.5 ppb
2019-12-1027.8 ppb
2019-12-1032.5 ppb

* Sample result is taken from the system's CCR report.