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EWG's Tap Water Database — 2019 UPDATE

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N-Nitrosodimethylamine (NDMA)

Washington Aqueduct Division

N-Nitrosodimethylamine is one of the DNA-damaging, cancer-causing contaminants called N-nitrosamines that can form during water treatment with the use of certain disinfectants, such as chloramine. Read More.

Pollution of water sources with effluent from municipal wastewater treatment plants and runoff from animal feeding operations contributes to nitrosamine formation. Fifteen different nitrosamines are listed as carcinogens in the U.S. Department of Health and Human Services National Toxicology Program Report on Carcinogens. The federal government has not set a legal limit for nitrosamines in drinking water and water utilities typically do not test for these contaminants. California has set a public health goal for one of the most common nitrosamines, N-nitrosodimethylamine or NDMA, at 0.003 parts per billion in drinking water, a concentration that corresponds to an estimated one-in-one-million cancer risk.

Click here to read more about disinfection byproducts.

 

50

Samples

0

Samples exceeding legal limit (MCL)

3

Samples exceeding
health guidelines

Testing results - average by year

 
YearAverage resultSamples takenDetectionsRange of results
20120.275 ppt81ND - 2.20 ppt
2013ND80ND
20140.625 ppt81ND - 5.00 ppt
20150.675 ppt82ND - 3.00 ppt
20162.29 ppt82ND - 10.00 ppt
2017ND100ND

ppt = parts per trillion

State and national drinking water standards and health guidelines

EWG Health Guideline 3 ppt

The EWG Health Guideline of 3 ppt for n-nitrosodimethylamine was defined by the California Office of Environmental Health Hazard Assessment as a public health goal, the level of a drinking water contaminant that does not pose a significant health risk. This health guideline protects against cancer.

ppt = parts per trillion

All test results

Date Lab ID Result
2012-01-01McMillanND
2012-01-01DalecarliaND
2012-04-01DalecarliaND
2012-04-01McMillanND
2012-07-01DalecarliaND
2012-07-01McMillanND
2012-10-01Dalecarlia2.20 ppt
2012-10-01McMillanND
2013-01-01DalecarliaND
2013-01-01McMillanND
2013-04-01DalecarliaND
2013-04-01McMillanND
2013-07-01McMillanND
2013-07-01DalecarliaND
2013-10-01DalecarliaND
2013-10-01McMillanND
2014-01-01DalecarliaND
2014-01-01McMillan5.00 ppt
2014-04-01DalecarliaND
2014-04-01McMillanND
2014-07-01DalecarliaND
2014-07-01McMillanND
2014-10-01DalecarliaND
2014-10-01McMillanND
2015-01-01DalecarliaND
2015-01-01McMillanND
2015-04-01DalecarliaND
2015-04-01McMillanND
2015-07-01DalecarliaND
2015-07-01McMillanND
2015-10-01McMillan3.00 ppt
2015-10-01Dalecarlia2.40 ppt
2016-01-01Dalecarlia10.00 ppt
2016-01-01McMillan8.30 ppt
2016-04-01DalecarliaND
2016-04-01McMillanND
2016-07-01DalecarliaND
2016-07-01McMillanND
2016-10-01McMillanND
2016-10-01DalecarliaND
2017-01-01DalecarliaND
2017-01-01McMillanND
2017-04-01DalecarliaND
2017-04-01McMillanND
2017-07-01DalecarliaND
2017-07-01McMillanND
2017-09-01DalecarliaND
2017-09-01McMillanND
2017-10-01DalecarliaND
2017-10-01McMillanND