EWG's Tap Water Database — 2019 UPDATE


Chromium (hexavalent)

Oak Park Water Service

Chromium (hexavalent) is a carcinogen that commonly contaminates American drinking water. Chromium (hexavalent) in drinking water may be due to industrial pollution or natural occurrences in mineral deposits and groundwater. Read more about chromium (hexavalent).





Samples exceeding legal limit (MCL)


Samples exceeding
health guidelines

Testing results - average by year

YearAverage resultSamples takenDetectionsRange of results
20120.268 ppb64ND - 1.11 ppb
20130.110 ppb770.0600 ppb - 0.260 ppb
20140.104 ppb144ND - 0.380 ppb
20150.478 ppb880.250 ppb - 0.680 ppb

ppb = parts per billion

State and national drinking water standards and health guidelines

EWG Health Guideline 0.02 ppb

The EWG Health Guideline of 0.02 ppb for chromium (hexavalent) 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 cancer.

ppb = parts per billion

All test results

Date Lab ID Result
2015-03-105C10079-01A0.540 ppb
2015-03-105C10079-03A0.680 ppb
2015-06-105F10079-03A0.580 ppb
2015-06-105F10079-01A0.570 ppb
2015-09-015I01105-03A0.460 ppb
2015-09-015I01105-01A0.480 ppb
2015-12-015L01133-03A0.250 ppb
2015-12-015L01133-01A0.260 ppb