EWG's Tap Water Database — 2021 UPDATE


Nitrate and nitrite

Piedmont Municpal Authority

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
20140.767 ppm330.620 ppm - 1.01 ppm
20150.700 ppm330.560 ppm - 0.920 ppm
20160.735 ppm220.570 ppm - 0.900 ppm
20170.790 ppm220.630 ppm - 0.950 ppm
20180.735 ppm220.600 ppm - 0.870 ppm
20190.935 ppm220.800 ppm - 1.07 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
2014-06-03044155.0011.01 ppm
2014-06-03044155.0020.620 ppm
2014-06-03044155.0030.670 ppm
2015-06-01057110.0010.920 ppm
2015-06-01057110.0020.560 ppm
2015-06-01057110.0030.620 ppm
2016-09-27SDWA-1069106-000.900 ppm
2016-09-27SDWA-1069108-000.570 ppm
2017-11-03SDWA-1207016-000.950 ppm
2017-11-03SDWA-1207018-000.630 ppm
2018-04-16SDWA-1251752-000.870 ppm
2018-04-16SDWA-1251754-000.600 ppm
2019-02-20SDWA-1340933-001.07 ppm
2019-02-20SDWA-1340935-000.800 ppm