EWG's Tap Water Database


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
20100.120 ppm110.120 ppm
20110.110 ppm110.110 ppm
20120.140 ppm110.140 ppm
20130.1000 ppm110.1000 ppm
20140.120 ppm110.120 ppm
20150.0780 ppm110.0780 ppm

ppm = parts per million.

State and national drinking water standards and health guidelines

Health Guideline 0.14 ppm

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

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
2010-06-08AB247040.120 ppm
2011-06-28AB491560.110 ppm
2012-08-01AB805190.140 ppm
2013-07-23AC015970.1000 ppm
2014-06-11AC269030.120 ppm
2015-06-23AC515250.0780 ppm