EWG's Tap Water Database — 2019 UPDATE



City of South Houston

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
20120.552 ppm550.420 ppm - 0.600 ppm
20130.192 ppm550.180 ppm - 0.200 ppm
20140.740 ppm550.710 ppm - 0.810 ppm
20150.304 ppm550.290 ppm - 0.310 ppm
20160.550 ppm550.540 ppm - 0.560 ppm
20170.666 ppm550.250 ppm - 0.820 ppm

ppm = parts per million

State and national drinking water standards and health guidelines

EWG Health Guideline 0.14 ppm

The EWG Health Guideline of 0.14 ppm for nitrate was defined by EWG . This health guideline protects against cancer and harm to fetal growth and development.

EPA Maximum Contaminant
Level (MCL) 10 ppm

The legal limit for nitrate, established in 1962, was developed to protect infants from acute methemoglobinemia, a life-threatening disorder of oxygen transport in the body. This limit does not fully protect against the risk of cancer and harm to the developing fetus.

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
2013-01-14AC075390.190 ppm
2013-01-14AC075310.200 ppm
2013-01-14AC075400.200 ppm
2013-01-14AC075380.190 ppm
2013-01-14AC075360.180 ppm
2014-01-14AC387000.730 ppm
2014-01-14AC387010.730 ppm
2014-01-14AC386930.710 ppm
2014-01-14AC386990.810 ppm
2014-01-14AC387020.720 ppm
2015-01-21AC769860.290 ppm
2015-01-21AC769870.310 ppm
2015-01-21AC769850.300 ppm
2015-01-21AC769840.310 ppm
2015-01-21AC769830.310 ppm
2016-01-14AD180750.540 ppm
2016-01-14AD180780.560 ppm
2016-01-14AD180740.540 ppm
2016-01-14AD180760.560 ppm
2016-01-14AD180770.550 ppm
2017-01-06AD634530.250 ppm
2017-02-10AD702410.660 ppm
2017-03-01AD726570.820 ppm
2017-03-01AD726580.790 ppm
2017-03-01AD726560.810 ppm