If your water spots are from washing simply use DeIonized water or distilled water. If its rain spots, then follow advice above. I use waterless wash to get rid of spots as soon as possible using DI water and follow that with Turtle Wax T-9 1-Step Wax & Dry (
https://www.amazon.com/dp/B0007TV6M0). I have graphene on my vehicle and as was pointed out above, it does not prevent water spots on its own. Tap water is the worst if you have high dissolved solids and is best avoided.