EWG's Tap Water Database — 2019 UPDATE


Chromium (total)

Oak Park Water Service

Chromium is a naturally occurring metal, but industrial uses can elevate its levels in water. One form, hexavalent chromium, causes cancer. Total chromium is not a good indicator of the amount of hexavalent chromium in drinking water.





Samples exceeding legal limit (MCL)


Samples exceeding
health guidelines

Testing results - average by year

YearAverage resultSamples takenDetectionsRange of results
20120.167 ppb61ND - 1.000 ppb
20130.286 ppb71ND - 2.00 ppb
20140.250 ppb81ND - 2.00 ppb
20150.609 ppb880.400 ppb - 0.820 ppb
20161.000 ppb85ND - 2.00 ppb
20175.25 ppb81ND - 42.0 ppb

ppb = parts per billion

State and national drinking water standards and health guidelines

EPA Maximum Contaminant
Level (MCL) 100 ppb

The legal limit for total chromium, established in 1991, was based on a 1958 toxicity study in laboratory animals, and applies to both the less-toxic trivalent chromium and the more-toxic hexavalent chromium forms of this compound. This limit does not protect against the risk of cancer from ingestion of hexavalent chromium.

ppb = parts per billion

All test results

Date Lab ID Result
2015-03-105C10079-01A0.820 ppb
2015-03-105C10079-03A0.820 ppb
2015-06-105F10079-03A0.580 ppb
2015-07-075G07116-01A0.540 ppb
2015-09-015I01105-03A0.530 ppb
2015-09-015I01105-01A0.670 ppb
2015-12-015L01133-01A0.400 ppb
2015-12-015L01133-03A0.510 ppb