EWG's Tap Water Database — 2021 UPDATE



US Air Force Academy

Hexachlorocyclopentadiene was historically used for the manufacture of currently banned pesticides, such as endrin, dieldrin and chlordane. It’s still used for production of flame retardants, resins and plastics.





Samples exceeding legal limit (MCL)


Samples exceeding
health guidelines

Testing results - average by year

YearAverage resultSamples takenDetectionsRange of results
20140.0250 ppb21ND - 0.0500 ppb
20150.0190 ppb31ND - 0.0570 ppb
20160.0128 ppb123ND - 0.0700 ppb
20170.0210 ppb62ND - 0.0740 ppb
20190.00480 ppb101ND - 0.0480 ppb

ppb = parts per billion

State and national drinking water standards and health guidelines

EWG Health Guideline 2 ppb

The EWG Health Guideline of 2 ppb for hexachlorocyclopentadiene 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 harm to the stomach and intestines.

EPA Maximum Contaminant
Level (MCL) 50 ppb

The legal limit for hexachlorocyclopentadiene, established in 1992, was based on a toxicity study in laboratory animals conducted in the 1980s.

ppb = parts per billion

All test results

Date Result