6. Tallahassee, FL
Contaminants detected above health guidelines: 4
You have seen before that one of the worst US tap water comes from Florida, but here we have the city of Tallahassee which makes a better picture of Florida. Tap water of Tallahassee contains some harmful chemical, four of which are above health guidelines: chromium, radiological contaminants, tetrachloroethylene (perchloroethylene) and trihalomethanes.