EWG's Tap Water Database — 2021 UPDATE



Harris County Municipal Utility District 158

Endrin is a banned organochlorine insecticide that is persistent and bioaccumulative. Endrin damages the nervous, immune and reproductive systems in people. It also harms fish, birds and other wildlife.





Samples exceeding legal limit (MCL)


Samples exceeding
health guidelines

Testing results - average by year

YearAverage resultSamples takenDetectionsRange of results

ppb = parts per billion

State and national drinking water standards and health guidelines

EWG Health Guideline 0.3 ppb

The EWG Health Guideline of 0.3 ppb for endrin was defined by the California Office of Environmental Health Hazard Assessment as a public health goal, the level of a drinking water contaminant that does not pose a significant health risk. This health guideline protects against change to the heart and blood vessels.

EPA Maximum Contaminant
Level (MCL) 2 ppb

The legal limit for endrin, established in 1992, was based on a toxicity study in laboratory animals conducted in the 1960s.

ppb = parts per billion

All test results

Date Lab ID Result