The tap water in some cities might pose health risks to vulnerable consumers --people who have serious immune system problems, pregnant women, parents of infants, those with chronic illnesses and the elderly should consult with their health care providers about the safety of tap water.

"Our municipal water supplies are in danger all over the U.S., [hexavalent chromium] is a chemical that should be regulated."

"It is not uncommon for people to drink tap water laced with 20 or 30 chemical contaminants. This water may be legal, but it raises serious health concerns.

Since 2004, the water provided to more than 49 million people has contained illegal concentrations of chemicals like arsenic or radioactive substances like uranium, as well as dangerous bacteria often found in sewage.

“The same people who told us to ignore Safe Drinking Water Act violations are still running the divisions,” said one mid-level E.P.A. official. “There’s no accountability, and so nothing’s going to change.”