EWG's Tap Water Database — 2019 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
20120.273 ppm43ND - 0.410 ppm
20130.360 ppm440.310 ppm - 0.420 ppm
20140.353 ppm440.310 ppm - 0.410 ppm
20150.368 ppm440.320 ppm - 0.420 ppm
20160.348 ppm440.310 ppm - 0.390 ppm
20170.364 ppm550.310 ppm - 0.400 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
2012-01-10P01120630.380 ppm
2012-01-10P01120640.300 ppm
2012-01-10P01120650.410 ppm
2013-03-05C13-03-00290.420 ppm
2013-03-05C13-03-00280.320 ppm
2013-03-05C13-03-00270.390 ppm
2013-03-05C13-03-00260.310 ppm
2014-01-22C14-01-00140.380 ppm
2014-01-22C14-01-00150.310 ppm
2014-01-22C14-01-00160.410 ppm
2014-01-22C14-01-00170.310 ppm
2015-02-04C15-02-00330.420 ppm
2015-02-04C15-02-00320.320 ppm
2015-02-04C15-02-00310.390 ppm
2015-02-04C15-02-00300.340 ppm
2016-03-220.330 ppm
2016-03-220.310 ppm
2016-03-220.390 ppm
2016-03-220.360 ppm
2017-03-140.400 ppm
2017-03-140.380 ppm
2017-03-140.310 ppm
2017-03-140.340 ppm
2017-05-090.390 ppm