EWG's Tap Water Database — 2021 UPDATE


Nitrate and nitrite

Choctaw Utilities Inc.

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
20140.608 ppm440.300 ppm - 1.05 ppm
20150.348 ppm440.280 ppm - 0.390 ppm
20160.665 ppm220.580 ppm - 0.750 ppm
20170.725 ppm220.700 ppm - 0.750 ppm
20180.330 ppm21ND - 0.660 ppm
20190.795 ppm220.630 ppm - 0.960 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
2014-01-27A1401477120.300 ppm
2014-04-15A1400413180.600 ppm
2014-07-15A1402015790.480 ppm
2014-10-20A1402405671.05 ppm
2015-01-20A1502591430.350 ppm
2015-04-21A1502777960.370 ppm
2015-07-28A1502233120.390 ppm
2015-12-15A1503192540.280 ppm
2016-06-21A1604126010.580 ppm
2016-11-28A1601205710.750 ppm
2017-09-26A1705348840.750 ppm
2017-11-21A1705479940.700 ppm
2018-11-198K02322-010.660 ppm
2019-07-169G02462-030.630 ppm
2019-10-159J02375-010.960 ppm