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EWG's Tap Water Database — 2021 UPDATE

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Total trihalomethanes (TTHMs)

Sands Point

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

 

142

Samples

0

Samples exceeding legal limit (MCL)

32

Samples exceeding
health guidelines

Testing results - average by year

 
YearAverage resultSamples takenDetectionsRange of results
2014ND200ND
2015ND190ND
20160.586 ppb233ND - 6.84 ppb
20170.269 ppb2910ND - 1.10 ppb
20181.01 ppb268ND - 11.3 ppb
20190.633 ppb2511ND - 6.90 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
2014-03-111403728-002-POCSND
2014-03-111403728-003-POCSND
2014-03-111403728-004-POCSND
2014-03-111403728-005-POCSND
2014-03-111403728-001-POCSND
2014-05-131405909-002-POCSND
2014-05-131405909-005-POCSND
2014-05-131405909-001-POCSND
2014-05-131405909-004-POCSND
2014-05-131405909-003-POCSND
2014-09-021409077-002-POCSND
2014-09-021409077-001-POCSND
2014-09-021409077-004-POCSND
2014-09-02140907-003-POCSND
2014-09-021409077-005-POCSND
2014-11-181411C18-003-POCSND
2014-11-181411C18-002-POCSND
2014-11-181411C18-005-POCSND
2014-11-181411C18-001-POCSND
2014-11-181411C18-004-POCSND
2015-03-171503B53-002-POCSND
2015-03-171503B53-004-POCSND
2015-03-171503B53-001-POCSND
2015-03-171503B53-003-POCSND
2015-03-171503B53-005-POCSND
2015-06-161506D36-005-POCSND
2015-06-161506D36-002-POCSND
2015-06-161506D36-004-POCSND
2015-06-161506D36-001-POCSND
2015-06-161506D36-003-POCSND
2015-09-221509H02-004-POCSND
2015-09-221509H02-002-POCSND
2015-09-221509H02-003-POCSND
2015-09-221509H02-001-POCSND
2015-09-221509H02-005-POCSND
2015-11-171511D82-002-POCSND
2015-11-171511D82-004-POCSND
2015-11-171511D82-003-POCSND
2015-11-171511D82-001-POCSND
2016-03-221603H56-005-POCSND
2016-03-221603H56-004ND
2016-03-221603H56-002ND
2016-03-221603H56-001-POCSND
2016-03-221603H56-003ND
2016-05-051605483-0046.84 ppb
2016-05-231605L07-005ND
2016-05-231605L07-002ND
2016-05-231605L07-001ND
2016-05-231605L07-003ND
2016-05-231605L07-004ND
2016-09-261609M44-003ND
2016-09-261609M44-005ND
2016-09-261609M44-003AND
2016-09-261609M44-004ND
2016-09-261609M44-001ND
2016-11-16704726002ND
2016-12-01705820005-POCSND
2016-12-01705820005ND
2016-12-01705820002-POCND
2016-12-01705820001-POCS5.80 ppb
2016-12-01705820003-POCND
2016-12-01705820004-POC0.830 ppb
2017-03-217013839001ND
2017-03-287014322002AND
2017-03-287014322003ND
2017-03-287014322001-POCS0.570 ppb
2017-03-287014322004ND
2017-05-117018457003-POCS1.10 ppb
2017-05-167018796001ND
2017-05-167018796001-POCSND
2017-05-167018796004ND
2017-05-167018796004-POCSND
2017-05-167018796002ND
2017-05-167018796002-POCSND
2017-05-1670187960030.740 ppb
2017-05-167018796003-POCS0.740 ppb
2017-05-187019036001ND
2017-09-257030950004-POCS0.950 ppb
2017-09-257030950003-POCSND
2017-09-257030950006-POCSND
2017-09-257030950001-POCS0.730 ppb
2017-09-252902852-POCS0.950 ppb
2017-09-25703950001-POCS0.730 ppb
2017-09-257030950002-POCSND
2017-09-257030950005ND
2017-11-147035726002-POCSND
2017-11-147035726004-POCS0.630 ppb
2017-11-147035726003-POCSND
2017-11-147035726001-POCS0.660 ppb
2017-11-147035726006-POCSND
2017-11-147035726005-POCSND
2018-03-147045332006-POCSND
2018-03-147045332005-POCSND
2018-03-147045332004-POCSND
2018-03-147045332003-POCSND
2018-03-147045332002-POCSND
2018-03-147045332001-POCS0.590 ppb
2018-05-087050974003-POCSND
2018-05-087050974002-POCSND
2018-05-087050974005-POCSND
2018-05-087050974006-POCSND
2018-05-087050974001-POCS0.680 ppb
2018-05-087050974004-POCSND
2018-09-10706423500111.3 ppb
2018-09-1070642350026.10 ppb
2018-09-187065159003-POCSND
2018-09-187065159002-POCSND
2018-09-187065159006-POCSND
2018-09-187065159004-POCS0.930 ppb
2018-09-187065159005-POCSND
2018-09-187065159001-POCS0.710 ppb
2018-11-287072272004-POCS0.820 ppb
2018-11-287072272005-POCSND
2018-11-287072266001-POCSND
2018-11-287072272003-POCS5.20 ppb
2018-11-287072272002-POCSND
2018-11-2870772272001-POCSND
2019-03-197082847003ND
2019-03-197082847002ND
2019-03-1970828380010.840 ppb
2019-03-1970828380031.40 ppb
2019-03-1970828380020.930 ppb
2019-03-197082847001ND
2019-06-047092017004-POCS0.840 ppb
2019-06-047092017001-POCS0.670 ppb
2019-06-047092017005-POCSND
2019-06-047092017006-POCSND
2019-06-047092017002-POCSND
2019-06-047092017003-POCSND
2019-09-09701042080016.90 ppb
2019-09-17701052510040.820 ppb
2019-09-1770105251003-POCSND
2019-09-1770105251001-POCS0.610 ppb
2019-09-1770105251002-POCSND
2019-09-1770105251006ND
2019-09-1770105251005ND
2019-12-03701139240021.10 ppb
2019-12-03701139240011.10 ppb
2019-12-0370113924005ND
2019-12-03701139240030.620 ppb
2019-12-0370113924006ND
2019-12-1770113924004ND