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EWG's Tap Water Database — 2019 UPDATE

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Total trihalomethanes (TTHMs)

Lee County WSC

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.

In 2010, the California Office of Environmental Health Hazard Assessment published a draft public health goal for the trihalomethanes group at 0.8 parts per billion, or 100 times lower than the federal legal limit of 80 parts per billion for this contaminant group.

Click here to read more about disinfection byproducts.

 

70

Samples

0

Samples exceeding legal limit (MCL)

18

Samples exceeding
health guidelines

Testing results - average by year

 
YearAverage resultSamples takenDetectionsRange of results
2012N/A00N/A
20130.790 ppb61ND - 4.74 ppb
20141.24 ppb163ND - 7.30 ppb
20151.91 ppb165ND - 14.5 ppb
20161.93 ppb165ND - 12.8 ppb
20170.869 ppb164ND - 5.20 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
2013-10-14Q1308854031ND
2013-10-14Q1308854019ND
2013-10-14Q1308854008ND
2013-10-14Q13088540074.74 ppb
2013-10-14Q1308854006ND
2013-10-14Q1308854005ND
2014-02-25AC44498ND
2014-02-25AC44479ND
2014-02-25AC444777.30 ppb
2014-02-25AC44480ND
2014-05-13AC54048ND
2014-05-13AC540496.00 ppb
2014-05-13AC54047ND
2014-05-13AC54050ND
2014-08-14AC63796ND
2014-08-14AC63792ND
2014-08-14AC637956.50 ppb
2014-08-14AC63807ND
2014-12-08AC73988ND
2014-12-08AC73982ND
2014-12-08AC73981ND
2014-12-08AC73987ND
2015-03-04AC82665ND
2015-03-04AC827341.10 ppb
2015-03-04AC8266614.5 ppb
2015-03-04AC82662ND
2015-06-17AC96240ND
2015-06-17AC96252ND
2015-06-17AC96251ND
2015-06-17AC962537.60 ppb
2015-09-01AD05131ND
2015-09-01AD051391.10 ppb
2015-09-01AD05137ND
2015-09-01AD05145ND
2015-11-13AD13546ND
2015-11-13AD13549ND
2015-11-13AD13550ND
2015-11-13AD135856.30 ppb
2016-01-27AD20344ND
2016-01-27AD20346ND
2016-01-27AD203455.00 ppb
2016-01-27AD20347ND
2016-04-12AD32765ND
2016-04-12AD32766ND
2016-04-12AD32770ND
2016-04-12AD327683.90 ppb
2016-07-26AD45662ND
2016-07-26AD456672.90 ppb
2016-07-26AD45665ND
2016-07-26AD45660ND
2016-10-31AD55452ND
2016-10-31AD554536.30 ppb
2016-10-31AD5545412.8 ppb
2016-10-31AD55457ND
2017-01-30AD67510ND
2017-01-30AD675113.70 ppb
2017-01-30AD67506ND
2017-01-30AD67509ND
2017-04-11AD79180ND
2017-05-04AD82730ND
2017-05-04AD827315.20 ppb
2017-05-04AD82732ND
2017-07-24AD903273.90 ppb
2017-07-24AD90322ND
2017-07-24AD90323ND
2017-07-24AD90326ND
2017-10-04AD99243ND
2017-10-04AD99235ND
2017-10-04AD992361.10 ppb
2017-10-04AD99231ND