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
20140.293 ppm330.0700 ppm - 0.480 ppm
20150.330 ppm330.0900 ppm - 0.600 ppm
20160.183 ppm330.0600 ppm - 0.360 ppm
20170.0433 ppm330.0300 ppm - 0.0700 ppm
20180.0733 ppm330.0400 ppm - 0.130 ppm
20190.0700 ppm330.0400 ppm - 0.1000 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
2014-04-034040603-020.330 ppm
2014-04-034040603-030.0700 ppm
2014-04-034040603-010.480 ppm
2015-04-065040613-010.600 ppm
2015-04-065040613-020.300 ppm
2015-04-065040613-030.0900 ppm
2016-04-256043725-010.360 ppm
2016-04-256043725-020.130 ppm
2016-04-256043725-030.0600 ppm
2017-06-147062452-020.0700 ppm
2017-06-147062452-030.0300 ppm
2017-06-147062452-010.0300 ppm
2018-06-068060976-010.0400 ppm
2018-06-068060976-020.130 ppm
2018-06-068060976-030.0500 ppm
2019-04-089041796-010.1000 ppm
2019-04-089041796-020.0400 ppm
2019-04-089041796-030.0700 ppm