Recent laboratory tests commisioned by the Environmental Working Group have found hexavalent chromium in the tap water of 31 cities. More disturbing still is the fact that the tap water from only 35 cities was sampled for the cancer-causing chemical, meaning it was found in 89 percent of the cities tested. The EWG estimates that 74 million Americans in 42 states could be drinking tap water that is polluted with chromium or its carcinogenic form, hexavalent chromium.
The Environmental Protection Agency allows for 100 parts per billion of total chromium in drinking water, but it has not set a safe or acceptable limit for hexavalent chromium, the cancer-causing variant of chromium. As such, water utility companies are not required to test for hexavalent chromium. California is the only state that requires such testing, and it has set a legal limit of .06 parts per billion. Of the 31 cities that had hexavalent chromium, 25 cities had levels higher than that amount.
Currently, the EPA maintains a Maximum Contaminant Level (MCL) of 100 parts per billion for total Chromium, but they do not test specifically for the carcinogenic variant hexavalent chromium.