EWG's Tap Water Database — 2021 UPDATE



University of West Florida

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
20140.340 ppm220.330 ppm - 0.350 ppm
20150.310 ppm220.290 ppm - 0.330 ppm
20160.295 ppm220.280 ppm - 0.310 ppm
20170.355 ppm220.340 ppm - 0.370 ppm
20180.320 ppm220.310 ppm - 0.330 ppm
20190.320 ppm220.320 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 Result
2014-10-290.350 ppm
2014-10-290.330 ppm
2015-08-120.330 ppm
2015-08-120.290 ppm
2016-08-160.310 ppm
2016-08-160.280 ppm
2017-10-250.340 ppm
2017-10-250.370 ppm
2018-11-190.310 ppm
2018-11-190.330 ppm
2019-09-170.320 ppm
2019-09-170.320 ppm