Yep, like everyone has said above. Try vinegar first (found at your local grocery store). If that doesn't work, claybar should do the trick. If that still doesn't work, it's most likely etched into your paint and you're going to have to use a mild polish to get it out. In the future, you can also buy Duragloss Water Spot Remover; heard it works like a charm. The water spots will eventually come out; I know -- I've had them before!