EWG's Tap Water Database — 2019 UPDATE


Nitrate and nitrite


Nitrate and nitrite enter water from fertilizer runoff, septic tanks and urban runoff. These contaminants can cause oxygen deprivation for infants and increase the risk of cancer. Nitrite is significantly more toxic than nitrate. Click here to read more about nitrate.





Samples exceeding legal limit (MCL)


Samples exceeding
health guidelines

Testing results - average by year

YearAverage resultSamples takenDetectionsRange of results
20120.0300 ppm110.0300 ppm
20130.0240 ppm110.0240 ppm
20140.0180 ppm110.0180 ppm
20150.130 ppm110.130 ppm
20160.160 ppm110.160 ppm
20170.0410 ppm110.0410 ppm

ppm = parts per million

State and national drinking water standards and health guidelines

EWG Health Guideline 0.14 ppm

The health guideline of 0.14 parts per million, or ppm, for nitrate and nitrite is based on the equivalent health guideline for nitrate, as defined in a peer-reviewed scientific study by EWG. This guideline represents a one-in-one-million annual cancer risk level.

EPA Maximum Contaminant
Level (MCL) 10 ppm

ppm = parts per million

All test results

Date Lab ID Result
2012-11-29AB865670.0300 ppm
2013-11-05AC144540.0240 ppm
2014-11-19AC385100.0180 ppm
2015-03-16AC438670.130 ppm
2016-03-07AC678700.160 ppm
2017-03-14AC922980.0410 ppm