EWG's Tap Water Database


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
20100.300 ppm220.288 ppm - 0.311 ppm
20110.417 ppm220.393 ppm - 0.440 ppm
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

ppm = parts per million.

State and national drinking water standards and health guidelines

Health Guideline 5 ppm

The health guideline of 5 ppm for nitrate and nitrite was defined by EWG based on studies by scientists at the National Cancer Institute and other independent researchers. This health guideline protects against cancer and harm to fetal growth and development.

ppm = parts per million.

EPA Maximum Contaminant
Level (MCL) 10 ppm

The enforceable federal standard that defines the highest level of a contaminant allowed in drinking water.

ppm = parts per million.

EPA Maximum Contaminant
Level Goal (MCLG)10 ppm

A non-enforceable federal health guideline. For cancer-causing chemicals, these health goals are typically set to zero.

ppm = parts per million.

All test results

Date Lab ID Result
2010-05-04SE00130-01_010.288 ppm
2010-05-04SE00130-02_010.311 ppm
2011-05-03SE10148-02_010.393 ppm
2011-05-03SE10148-01_010.440 ppm
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