EWG's Tap Water Database



Clearwater Water System

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
20100.0940 ppm330.0320 ppm - 0.130 ppm
20110.0900 ppm330.0300 ppm - 0.160 ppm
20120.0800 ppm330.0300 ppm - 0.130 ppm
20130.1000 ppm330.0400 ppm - 0.160 ppm
20140.130 ppm110.130 ppm
20150.0800 ppm330.0300 ppm - 0.140 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 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 Result
2010-02-100.130 ppm
2010-02-100.0320 ppm
2010-02-110.120 ppm
2011-02-160.160 ppm
2011-02-160.0300 ppm
2011-02-160.0800 ppm
2012-02-100.0300 ppm
2012-02-100.130 ppm
2012-02-100.0800 ppm
2013-02-010.160 ppm
2013-02-010.1000 ppm
2013-02-010.0400 ppm
2014-02-130.130 ppm
2015-01-130.0700 ppm
2015-01-130.0300 ppm
2015-05-070.140 ppm