Most manufacturers that I know of allow clean drinkable water to be used, and they prefer the cleanest water available. If you are in doubt, just pour a glass and set it aside to evaporate (unless you are in England, where the glass will get MORE water in it with time! ;-) )
In any case, the amount of water used in a wash is small, and the encrustation from that water would be small, especially as compared to the enormous mineral content of the salt air and spray that are the reasons why you rinse.