EWG's Tap Water Database — 2019 UPDATE


Nitrate and nitrite

City of South Houston

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
20120.552 ppm550.420 ppm - 0.600 ppm
20130.192 ppm550.180 ppm - 0.200 ppm
20150.320 ppm550.300 ppm - 0.340 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
2012-02-06AB802000.590 ppm
2012-02-06AB801970.420 ppm
2012-02-06AB802070.580 ppm
2012-02-06AB802030.600 ppm
2012-02-06AB802020.570 ppm
2013-01-14AC075360.180 ppm
2013-01-14AC075380.190 ppm
2013-01-14AC075400.200 ppm
2013-01-14AC075310.200 ppm
2013-01-14AC075390.190 ppm
2015-01-21AC769860.300 ppm
2015-01-21AC769870.340 ppm
2015-01-21AC769850.300 ppm
2015-01-21AC769840.330 ppm
2015-01-21AC769830.330 ppm