Why does the water leave stains?
A. Tap water has to be made safe for human consumption. and to do this, they have to add all sorts of things to kill off the bacteria and microorganisms. Chemicals such as Chlorine, Fluorine compounds, Trihalomethanes, Salts, and Nitrates, are all added. Once the water is on the car, the sun will evaporate the liquid, leaving behind white stains, that are really quite hard to remove.
