California

The Golden State's local water systems showed 145 contaminants, nearly half of which exceeded health limits set forth by the EPA. A majority of the people who use this water were exposed to this water that was primarily contaminated by industrial waste, like nitrate, and to a lesser extent acetone and lithium -- substances for which the EPA has not established a legal limit.

For the full report, including affected communities and state breakdowns visit http://www.ewg.org/tapwater/national/.