EWG's Tap Water Database — 2021 UPDATE




Nitrate, a fertilizer chemical, frequently contaminates drinking water due to agricultural and urban runoff, and discharges from municipal wastewater treatment plants and septic tanks. Excessive nitrate in water can cause oxygen deprivation in infants and increase the risk of cancer. 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
20140.230 ppm110.230 ppm
20150.360 ppm110.360 ppm
20160.590 ppm110.590 ppm
20170.0800 ppm110.0800 ppm
20180.440 ppm110.440 ppm
20190.0400 ppm110.0400 ppm

ppm = parts per million

State and national drinking water standards and health guidelines

EWG Health Guideline 0.14 ppm

The EWG Health Guideline of 0.14 ppm for nitrate was defined by EWG . This health guideline protects against cancer and harm to fetal growth and development.

EPA Maximum Contaminant
Level (MCL) 10 ppm

The legal limit for nitrate, established in 1962, was developed to protect infants from acute methemoglobinemia, a life-threatening disorder of oxygen transport in the body. This limit does not fully protect against the risk of cancer and harm to the developing fetus.

ppm = parts per million

All test results

Date Lab ID Result
2014-07-244073676-010.230 ppm
2015-07-065070617-010.360 ppm
2016-07-116071479-010.590 ppm
2017-08-077081403-010.0800 ppm
2018-07-028070187-010.440 ppm
2019-07-019070163-010.0400 ppm