EWG's Tap Water Database — 2019 UPDATE


Nitrate and nitrite

City of Chicago

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
20120.342 ppm220.340 ppm - 0.343 ppm
20130.357 ppm220.351 ppm - 0.362 ppm
20140.306 ppm220.304 ppm - 0.308 ppm
20150.290 ppm220.280 ppm - 0.299 ppm
20160.434 ppm220.405 ppm - 0.462 ppm
20170.340 ppm220.321 ppm - 0.359 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
2012-05-07SE20355-01_010.343 ppm
2012-05-07SE20355-02_010.340 ppm
2013-04-30SE30009-01_010.351 ppm
2013-04-30SE30009-02_010.362 ppm
2014-05-13SE40612-01_010.304 ppm
2014-05-13SE40612-02_010.308 ppm
2015-06-01SF50061-01_010.299 ppm
2015-06-01SF50061-02_010.280 ppm
2016-05-0316E0144-01_010.462 ppm
2016-05-0316E0144-02_010.405 ppm
2017-05-0217E0094-01_010.321 ppm
2017-05-0217E0094-02_010.359 ppm