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
20120.907 ppm770.310 ppm - 2.23 ppm
20130.726 ppm770.380 ppm - 1.38 ppm
20140.736 ppm770.320 ppm - 1.28 ppm
20150.664 ppm770.310 ppm - 1.31 ppm
20160.681 ppm770.280 ppm - 1.29 ppm
20170.754 ppm770.0510 ppm - 1.39 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
2012-08-08AB815200.740 ppm
2012-08-08AB815210.310 ppm
2012-08-08AB815220.830 ppm
2012-08-08AB815230.830 ppm
2012-08-08AB815242.23 ppm
2012-08-08AB815250.750 ppm
2012-08-08AB815190.660 ppm
2013-08-27AC076630.660 ppm
2013-08-27AC076640.680 ppm
2013-08-27AC076620.920 ppm
2013-08-27AC076610.380 ppm
2013-08-27AC076600.600 ppm
2013-08-27AC076590.460 ppm
2013-08-27AC076581.38 ppm
2014-08-21AC321090.320 ppm
2014-08-21AC321101.28 ppm
2014-08-21AC321111.25 ppm
2014-08-21AC321120.610 ppm
2014-08-21AC321130.720 ppm
2014-08-21AC321140.370 ppm
2014-08-25AC321150.600 ppm
2015-02-19AC423730.380 ppm
2015-02-19AC423710.380 ppm
2015-02-19AC423740.430 ppm
2015-02-19AC423720.310 ppm
2015-02-19AC423691.20 ppm
2015-02-19AC423750.640 ppm
2015-02-19AC423701.31 ppm
2016-02-29AC665650.700 ppm
2016-02-29AC665640.700 ppm
2016-02-29AC665631.29 ppm
2016-02-29AC665660.720 ppm
2016-02-29AC665680.630 ppm
2016-02-29AC665690.280 ppm
2016-02-29AC665670.450 ppm
2017-02-16AC912311.12 ppm
2017-02-16AC912300.770 ppm
2017-02-16AC912270.830 ppm
2017-02-16AC912290.740 ppm
2017-02-16AC912250.0510 ppm
2017-02-16AC912261.39 ppm
2017-02-16AC912280.380 ppm