EWG's Tap Water Database — 2019 UPDATE


Nitrate and nitrite

Clarksville Waterworks

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
20120.520 ppm220.520 ppm
20130.250 ppm110.250 ppm
20140.490 ppm220.480 ppm - 0.500 ppm
20150.330 ppm110.330 ppm
20160.370 ppm110.370 ppm
20170.120 ppm110.120 ppm

ppm = parts per million

State and national drinking water standards and health guidelines

EWG Health Guideline 0.14 ppm

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

EPA Maximum Contaminant
Level (MCL) 10 ppm

ppm = parts per million

All test results

Date Lab ID Result
2012-01-04Y1200600070.520 ppm
2012-01-041200600070.520 ppm
2013-01-031300400150.250 ppm
2014-02-261405800010.500 ppm
2014-03-101407200210.480 ppm
2015-02-02Y1503700010.330 ppm
2016-01-05Y1600800780.370 ppm
2017-02-01Y1703300060.120 ppm