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EWG's Tap Water Database — 2021 UPDATE

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Total trihalomethanes (TTHMs)

New York American Water - Sea Cliff

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

 

137

Samples

0

Samples exceeding legal limit (MCL)

4

Samples exceeding
health guidelines

Testing results - average by year

 
YearAverage resultSamples takenDetectionsRange of results
2014ND170ND
2015ND190ND
2016ND200ND
2017ND150ND
20180.140 ppb323ND - 2.70 ppb
20190.0738 ppb341ND - 2.51 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
2014-02-041402068-001-POCSND
2014-03-06103383-003-POCSND
2014-03-061403383-001-POCSND
2014-03-061403383-003-POCSND
2014-04-0204187-001-POCSND
2014-04-021404187-001-POCSND
2014-04-021404187-003-POCSND
2014-05-071405474-001-POCSND
2014-06-101406727-001-POCSND
2014-07-081407443-001-POCSND
2014-07-081407443-003-POCSND
2014-08-05140828-001-POCSND
2014-09-081409505-001-POCSND
2014-10-071410466-001-POCSND
2014-10-071410466-003-POCSND
2014-11-121411766-001-POCSND
2014-12-021412131-001-POCSND
2015-01-051501102-003-POCSND
2015-01-051501102-001-POCSND
2015-02-041502203-001-POCSND
2015-03-031503130-001-POCSND
2015-04-081504541-001-POCSND
2015-05-071505554-001-POCSND
2015-05-071505537-001-POCSND
2015-05-201505E69-001-POCSND
2015-06-151506B92-001-POCSND
2015-07-081507488-001ND
2015-07-081507488-003ND
2015-08-051508310-001 POCSND
2015-09-151509A69-001ND
2015-09-151509A69-003ND
2015-10-061510358-001ND
2015-10-061510358-003ND
2015-11-091511661-003ND
2015-11-091511661-001ND
2015-12-021512184-001ND
2016-01-111601562-001ND
2016-01-261601G80-001ND
2016-03-011603105-001ND
2016-03-011603105-003ND
2016-04-061604546-003ND
2016-04-061604546-001ND
2016-05-031605198-001ND
2016-05-031605198-003ND
2016-06-081606789-003ND
2016-06-081606789-001ND
2016-07-061607433-001ND
2016-07-061607433-003ND
2016-08-021608166-005ND
2016-08-021608166-002ND
2016-09-071609450-003ND
2016-09-071609450-001ND
2016-10-04701176002ND
2016-10-06701359002ND
2016-11-02703523001ND
2016-12-06706116001ND
2017-01-04708295001ND
2017-02-077010806001ND
2017-03-077012749001ND
2017-04-047014847001ND
2017-04-247016671002ND
2017-05-027017429001ND
2017-06-067020461001ND
2017-06-137021163001ND
2017-07-057023139003ND
2017-07-057023139001ND
2017-08-017025787002ND
2017-09-057028919001ND
2017-10-027031587001ND
2017-11-077035028001ND
2017-12-057037238001ND
2018-01-097039910001ND
2018-02-087042474001ND
2018-02-1370427710012.70 ppb
2018-02-1370427710030.600 ppb
2018-02-137042771004ND
2018-02-137042771002ND
2018-03-067044573001ND
2018-04-037047080001ND
2018-05-017050134001ND
2018-05-157051716001ND
2018-05-157051716004ND
2018-05-157051716002ND
2018-05-157051716003ND
2018-06-057053754001ND
2018-07-037057077003ND
2018-07-037057077001ND
2018-08-027060231003ND
2018-08-027060231001ND
2018-08-077060647001ND
2018-08-147061503002ND
2018-08-1470615030011.18 ppb
2018-08-147061503004ND
2018-08-147061503003ND
2018-09-047063575001ND
2018-10-027066538001ND
2018-10-097067280001ND
2018-11-197071544004ND
2018-11-197071544002ND
2018-11-197071544001ND
2018-11-197071544003ND
2018-11-287072200001ND
2018-12-197074419001ND
2019-01-157076606003ND
2019-01-157076606001ND
2019-02-057078364002ND
2019-02-0742960601ND
2019-02-0742960701ND
2019-02-0742960501ND
2019-02-0742960401ND
2019-03-197082788001ND
2019-04-027084234003ND
2019-04-027084234001ND
2019-05-147089459004ND
2019-05-147089459003ND
2019-05-147089462004ND
2019-05-1470894590022.51 ppb
2019-05-147089462001ND
2019-05-147089459001ND
2019-06-037091767001ND
2019-07-097096833001ND
2019-07-097096833003ND
2019-08-057099950003ND
2019-08-057099950001ND
2019-08-1670101654004ND
2019-08-1670101654002ND
2019-08-1670101654003ND
2019-08-1670101654001ND
2019-09-0370103523003ND
2019-09-0370103523001ND
2019-10-0270106994001ND
2019-10-2370109466001ND
2019-11-2170112750002ND
2019-11-2170112750001ND
2019-11-2170112750003ND
2019-11-2170112750004ND
2019-11-2570113095001ND