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EWG's Tap Water Database — 2021 UPDATE

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1,4-Dioxane

Norwalk Water Department

1,4-Dioxane is a solvent classified by the EPA as a likely human carcinogen. It contaminates groundwater in many states due to industrial wastewater discharges, plastic manufacturing runoff and landfill runoff. Read More.

Animal studies show that 1,4-dioxane can target the liver, kidneys and respiratory system, and that prenatal exposure can harm the developing fetus. The State of California has set a Public Heatlh Goal of no more than 1 part per billion of 1,4-dioxane in drinking water. The state of Massachusetts sets a legal limit of 0.3 ppb, and New Hampshire's limit is 3 parts per billion. There is no national drinking water standard for this contaminant.

Click here to read more about 1,4-dioxane.

MORE ABOUT THIS CONTAMINANT

 

65

Samples

0

Samples exceeding legal limit (MCL)

50

Samples exceeding
health guidelines

Testing results - average by year

 
YearAverage resultSamples takenDetectionsRange of results
20130.517 ppb184ND - 3.30 ppb
20144.85 ppb881.40 ppb - 7.60 ppb
20154.17 ppb661.60 ppb - 7.20 ppb
20163.69 ppb882.10 ppb - 5.80 ppb
20172.37 ppb98ND - 3.80 ppb
20182.21 ppb881.80 ppb - 2.50 ppb
20192.38 ppb881.60 ppb - 3.40 ppb

ppb = parts per billion

State and national drinking water standards and health guidelines

EWG Health Guideline 0.35 ppb

The EWG Health Guideline of 0.35 ppb for 1,4-dioxane was defined by the Environmental Protection Agency as a one-in-a-million lifetime risk of cancer. Values greater than one-in-a-million cancer risk level can result in increased cancer cases above one in a million people.

ppb = parts per billion

All test results

Date Lab ID Result
2013-01-31440-36867-33.30 ppb
2013-01-31440-36867-5ND
2013-01-31440-36867-7ND
2013-01-31440-36867-11.80 ppb
2013-04-30440-45114-5ND
2013-04-30440-45114-1ND
2013-04-30440-45114-3ND
2013-06-03440-47995-1ND
2013-06-03440-47995-2ND
2013-07-2928692942.10 ppb
2013-07-292869341ND
2013-07-2928693052.10 ppb
2013-07-292869322ND
2013-07-292869350ND
2013-07-292869359ND
2013-10-292922261ND
2013-10-292922281ND
2013-10-292922270ND
2014-02-199588-003-10003.00 ppb
2014-02-199588-002-10306.30 ppb
2014-04-299588-003-10182.90 ppb
2014-04-299588-002-10297.60 ppb
2014-07-239588-003-10101.40 ppb
2014-07-239588-002-10257.60 ppb
2014-12-109588-003-09452.80 ppb
2014-12-109588-002-10207.20 ppb
2015-03-259588-003-09402.80 ppb
2015-03-259588-002-09537.20 ppb
2015-04-239588-002-10415.80 ppb
2015-04-239588-003-10241.80 ppb
2015-07-309588-002-10445.80 ppb
2015-07-309588-003-10151.60 ppb
2016-03-249588-002-10245.80 ppb
2016-03-249588-003-10102.70 ppb
2016-06-099588-002-09455.20 ppb
2016-06-099588-003-09232.20 ppb
2016-07-209588-002-10154.60 ppb
2016-07-209588-003-09452.10 ppb
2016-10-129588-002-09574.50 ppb
2016-10-129588-003-09282.40 ppb
2017-01-189588-003-09202.30 ppb
2017-01-189588-002-09353.80 ppb
2017-04-179588-003-09522.20 ppb
2017-04-179588-002-09302.80 ppb
2017-07-249588-003-09552.50 ppb
2017-07-249588-002-10283.10 ppb
2017-10-189588-012-0914ND
2017-10-189588-003-09401.90 ppb
2017-10-189588-002-09502.70 ppb
2018-01-249588-002-09402.40 ppb
2018-01-249588-003-09202.50 ppb
2018-04-119588-003-09302.50 ppb
2018-04-119588-002-09532.10 ppb
2018-07-259588-003-09351.80 ppb
2018-07-259588-002-10002.20 ppb
2018-10-269588-003-09202.10 ppb
2018-10-269588-002-09402.10 ppb
2019-01-239588-002-09502.50 ppb
2019-01-239588-003-09203.00 ppb
2019-04-259588-002-10301.70 ppb
2019-04-259588-003-10052.30 ppb
2019-07-259588-002-10352.40 ppb
2019-07-259588-003-10102.10 ppb
2019-10-259588-002-10003.40 ppb
2019-10-259588-003-10401.60 ppb