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EWG's Tap Water Database — 2021 UPDATE

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Total trihalomethanes (TTHMs)

Locust Valley 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.

MORE ABOUT THIS CONTAMINANT

 

148

Samples

0

Samples exceeding legal limit (MCL)

0

Samples exceeding
health guidelines

Testing results - average by year

 
YearAverage resultSamples takenDetectionsRange of results
2014ND310ND
2015ND100ND
2016ND320ND
2017ND230ND
2018ND280ND
2019ND240ND

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
2014-01-141401530-002-POCSND
2014-01-141401530-003-POCSND
2014-01-211401867-001-POCSND
2014-01-281401B19-001-POCSND
2014-02-041402057-001-POCSND
2014-03-251404038-001-POCSND
2014-04-011404038-002-POCSND
2014-04-141404990-001-POCSND
2014-04-211404E83-001-POCSND
2014-06-301406M11-002-POCSND
2014-07-291407K05-001-POCSND
2014-08-181408B71-002-POCSND
2014-08-251408H39-001-POCSND
2014-08-261408I37-002-POCSND
2014-08-261408I37-001-POCSND
2014-09-101409740-002-POCSND
2014-09-101409749-001-POCSND
2014-09-171409D34-001-POCSND
2014-09-171409D32-001-POCSND
2014-09-231409I18-02-POCSND
2014-09-231409I18-002-POCSND
2014-09-241409I49-001-POCSND
2014-10-011410013-001-POCSND
2014-10-011410013-002-POCSND
2014-10-131410838-001-POCSND
2014-10-131410838-002-POCSND
2014-10-201410C68-001-POCSND
2014-10-301410K24-001-POCSND
2014-10-301410K24-002-POCSND
2014-11-171411A56-001-POCSND
2014-12-091412671-002-POCSND
2015-01-051501067-001-POCSND
2015-01-121501548-001-POCSND
2015-01-141501747-001-POCSND
2015-01-141501747-002-POCSND
2015-02-111502661-002-POCSND
2015-04-071504381-002-POCSND
2015-04-081504522-002-POCSND
2015-04-081504522-001-POCSND
2015-04-141504968-002-POCSND
2015-04-201504E35-001-POCSND
2016-01-051601125-002-POCND
2016-01-051601125-001-POCND
2016-01-061601266-002-POCND
2016-01-111601539-001-POCND
2016-01-121601657-001-POCND
2016-02-021602109-003-POCND
2016-02-021602109-002-POCND
2016-02-101602805-001-POCND
2016-03-141603A46-001-POCND
2016-04-041604198-001-POCND
2016-04-041604198-002-POCND
2016-04-061604482-001ND
2016-04-061604482-002-POCND
2016-04-121604A67-002-POCND
2016-05-031605141-002-POCND
2016-05-041605297-001-POCND
2016-05-041605297-002-POCND
2016-07-051607162-002-POCND
2016-07-111607746-001-POCND
2016-08-041608502-002-POCND
2016-08-171608G37-001-POCND
2016-08-231608L71-001-POCND
2016-08-301608S10-001-POCND
2016-09-061609219-003-POCND
2016-09-061609219-002-POCND
2016-10-03701027002-POCND
2016-10-03701027003-POCND
2016-10-03701027001-POCND
2016-10-05701210002-POCND
2016-11-01703388001-POCND
2016-11-01703388002-POCND
2016-12-01705763001-POCND
2017-01-04708263001-POCND
2017-01-04708263002-POCND
2017-01-10708707002-POCND
2017-01-10708707001-POCND
2017-01-23709647001-POCND
2017-02-137011227001-POCND
2017-04-037014711001-POCND
2017-04-037014711002-POCND
2017-04-047014822001-POCND
2017-04-047014822002-POCND
2017-04-247016689001-POCND
2017-05-037017623001ND
2017-08-227027930001-POCND
2017-08-287028361001-POCND
2017-08-307028531001-POCND
2017-09-057028851001-POCND
2017-09-117029447001-POCND
2017-10-027031534002-POCND
2017-10-027031534001-POCND
2017-10-107032367001-POCND
2017-10-237033738002-POCND
2017-11-137035523001-POCND
2017-11-207036171001-POCND
2018-01-027039447001ND
2018-01-087039782001-POCND
2018-01-167040417001-POCND
2018-01-167040417002-POCND
2018-01-237041066001-POCND
2018-02-077042205001ND
2018-04-037046983001ND
2018-04-037046983002ND
2018-04-237049233001ND
2018-04-247049376001ND
2018-05-077050702003ND
2018-08-037060300001-POCND
2018-08-077060621001-POCND
2018-08-137061326001-POCND
2018-08-217062227001-POCND
2018-09-047063494001ND
2018-09-047063494003ND
2018-09-107064177001-POCND
2018-10-037066637001ND
2018-10-097067250001ND
2018-10-107067430001ND
2018-10-117067660002ND
2018-11-017069657001ND
2018-11-067070105002ND
2018-11-077070276001ND
2018-11-097070664001ND
2018-12-03N-01651ND
2018-12-057072903002ND
2019-01-077075684001ND
2019-01-087075827002ND
2019-01-157076591001ND
2019-01-227077223001ND
2019-01-287077683001ND
2019-01-287077683002ND
2019-02-067078576002ND
2019-04-027084211001ND
2019-04-027084211003ND
2019-04-087084930002ND
2019-04-087084930001ND
2019-05-077088231001ND
2019-05-077088231002ND
2019-05-087088556001ND
2019-05-137089227001ND
2019-07-087096670001ND
2019-08-217062227001-POCND
2019-09-0370103457001-POCND
2019-09-0970104153001ND
2019-09-0970104153002-POCND
2019-09-1070104367001ND
2019-10-0170106790001ND
2019-10-1570108388001ND
2019-10-2870109853001ND