EWG's Tap Water Database


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
20100.300 ppm110.300 ppm
20110.260 ppm110.260 ppm
20120.520 ppm220.520 ppm
20130.250 ppm110.250 ppm
20140.490 ppm220.480 ppm - 0.500 ppm
20150.330 ppm110.330 ppm

ppm = parts per million.

State and national drinking water standards and health guidelines

Health Guideline 5 ppm

The health guideline of 5 ppm for nitrate and nitrite was defined by EWG based on studies by scientists at the National Cancer Institute and other independent researchers. This health guideline protects against cancer and harm to fetal growth and development.

ppm = parts per million.

EPA Maximum Contaminant
Level (MCL) 10 ppm

The enforceable federal standard that defines the highest level of a contaminant allowed in drinking water.

ppm = parts per million.

EPA Maximum Contaminant
Level Goal (MCLG)10 ppm

A non-enforceable federal health guideline. For cancer-causing chemicals, these health goals are typically set to zero.

ppm = parts per million.

All test results

Date Lab ID Result
2010-01-041000700050.300 ppm
2011-01-041100600020.260 ppm
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