EWG's Tap Water Database — 2019 UPDATE



Arlington County

N-Nitrosodi-N-butylamine 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.





Samples exceeding legal limit (MCL)


Samples exceeding
health guidelines

Testing results - average by year

YearAverage resultSamples takenDetectionsRange of results
20120.000350 ppb81ND - 0.00280 ppb
20130.00125 ppb82ND - 0.00600 ppb
20140.000250 ppb81ND - 0.00200 ppb
20170.000270 ppb101ND - 0.00270 ppb

ppb = parts per billion

All test results

Date Lab ID Result