EWG's Tap Water Database — 2019 UPDATE




Nitrite, closely related to the fertilizer chemical nitrate, comes from urban runoff and from fertilizer applied to agricultural lands to pollute drinking water. Nitrite is significantly more toxic than nitrate. Excessive nitrite in water can cause oxygen deprivation in infants and increase the risk of cancer.





Samples exceeding legal limit (MCL)


Samples exceeding
health guidelines

Testing results - average by year

YearAverage resultSamples takenDetectionsRange of results
20120.0227 ppm365136ND - 0.160 ppm
20130.0172 ppm36473ND - 0.199 ppm
20140.00156 ppm3654ND - 0.152 ppm
20150.00581 ppm36510ND - 0.740 ppm
20160.000393 ppm3661ND - 0.144 ppm
20170.0106 ppm36518ND - 0.460 ppm

ppm = parts per million

State and national drinking water standards and health guidelines

EPA Maximum Contaminant
Level (MCL) 1 ppm

The legal limit for nitrite, established in 1991, was based on the rate of conversion of ingested nitrate into nitrite in adults. This limit may not fully protect against the risk of cancer due to nitrite exposure.

ppm = parts per million

All test results

Date Lab ID Result