EWG's Tap Water Database — 2019 UPDATE


Nitrate and nitrite

Carroll-Boone Water District

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
20120.340 ppm110.340 ppm
20130.350 ppm110.350 ppm
20140.240 ppm110.240 ppm
20150.190 ppm110.190 ppm
20160.250 ppm110.250 ppm
20170.170 ppm110.170 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
2012-04-181211100030.340 ppm
2013-04-091310200030.350 ppm
2014-04-071410000290.240 ppm
2015-05-12Y1513500010.190 ppm
2016-04-19Y1611200130.250 ppm
2017-04-27Y1711800070.170 ppm