I live in Tampa and the hard water is pretty bad. I got a few dime size water mark etched into the paint and windows from my neighbor sprinkler and after you clean it up, you can still the ring around it if you look closely.
Did you know that you that if you mix 1/4 cup of white vinegar and distill water into a spray bottle, you can use it to remove hard water spot. Unfortunately it wont remove the the ring around it if you leave the hard water siting on your paint for a couple of days. It is also a cheap alternative way to clean windows and works better then Windex or other glass cleaner.
If you have any good method to remove calcified hard water from paint then please by all mean share.
