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EWG's Tap Water Database — 2019 UPDATE

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Total trihalomethanes (TTHMs)

Johnson Utilities

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.

 

83

Samples

0

Samples exceeding legal limit (MCL)

56

Samples exceeding
health guidelines

Testing results - average by year

 
YearAverage resultSamples takenDetectionsRange of results
20123.21 ppb106ND - 17.8 ppb
20135.47 ppb1412ND - 34.7 ppb
20144.59 ppb76ND - 10.3 ppb
20152.82 ppb2012ND - 11.7 ppb
20162.86 ppb1610ND - 9.90 ppb
20173.18 ppb1610ND - 10.4 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
2012-08-292082438-03ND
2012-08-292082438-021.60 ppb
2012-08-292082438-0117.8 ppb
2012-08-302082438-083.10 ppb
2012-08-302082438-07ND
2012-08-302082438-06ND
2012-08-302082438-051.60 ppb
2012-08-302082438-047.50 ppb
2012-08-312082438-100.500 ppb
2012-08-312082438-09ND
2013-07-233072128-060.500 ppb
2013-07-233072128-018.40 ppb
2013-07-233072128-02ND
2013-07-233072128-031.10 ppb
2013-07-233072128-044.90 ppb
2013-07-233072128-051.000 ppb
2013-07-293072571-0434.7 ppb
2013-07-293072571-036.20 ppb
2013-07-293072571-022.00 ppb
2013-07-293072571-013.30 ppb
2013-11-143111256-040.900 ppb
2013-11-143111256-0112.0 ppb
2013-11-143111256-02ND
2013-11-143111256-031.60 ppb
2014-05-1440513962-018.00 ppb
2014-05-144051362-0410.3 ppb
2014-05-144051362-021.000 ppb
2014-11-104110867-04ND
2014-11-104110867-036.70 ppb
2014-11-104110867-020.600 ppb
2014-11-104110867-015.50 ppb
2015-02-175021649-040.900 ppb
2015-02-175021649-034.50 ppb
2015-02-175021649-02ND
2015-02-175021649-014.70 ppb
2015-05-135051232-03ND
2015-05-135051232-0411.2 ppb
2015-05-135051232-0510.1 ppb
2015-05-135051232-06ND
2015-05-135051232-07ND
2015-05-135051232-081.50 ppb
2015-05-135051232-02ND
2015-05-135051232-011.000 ppb
2015-08-185081782-040.900 ppb
2015-08-185081782-03ND
2015-08-185081782-02ND
2015-08-185081782-0111.7 ppb
2015-11-115111059-013.90 ppb
2015-11-115111059-02ND
2015-11-115111059-034.70 ppb
2015-11-115111059-041.30 ppb
2016-02-176021767-043.80 ppb
2016-02-176021767-03ND
2016-02-176021767-02ND
2016-02-176021767-011.30 ppb
2016-05-166051485-048.60 ppb
2016-05-166051485-03ND
2016-05-166051485-022.50 ppb
2016-05-166051485-019.30 ppb
2016-08-186081903-021.20 ppb
2016-08-186081903-01ND
2016-08-186081903-03ND
2016-08-186081903-043.90 ppb
2016-11-176111721-044.80 ppb
2016-11-176111721-030.500 ppb
2016-11-176111721-029.90 ppb
2016-11-176111721-01ND
2017-02-157021605-01ND
2017-02-157021605-021.10 ppb
2017-02-157021605-03ND
2017-02-157021605-041.70 ppb
2017-05-187052020-047.20 ppb
2017-05-187052020-03ND
2017-05-187052020-026.50 ppb
2017-05-187052020-010.600 ppb
2017-08-177082008-0410.4 ppb
2017-08-177082008-03ND
2017-08-177082008-029.80 ppb
2017-08-177082008-01ND
2017-11-157111764-025.30 ppb
2017-11-157111764-037.30 ppb
2017-11-157111764-04ND
2017-11-157111764-011.000 ppb