Water spots can easily be removed by using Gel-gloss. This product is cheap and sold at hardware stores to polish faux marble. I've used it in my home for over 14 years and on my cars for the last 10. It won't harm your clear coat.
It comes in a purple can as a thick liquid or a spray. Use the thick liquid for tougher spots. Do small areas. Apply with a damp cloth and buff with a clean one. Be sure and wax after using it.
2004 E60 530is, Delivered 12/12/03, TiSilver/LGrey, PP, SP,PS, PDC, ACC, FRS, Step, Xenons, clear bra, body colored rear inserts. (Retired, 1983 henna red 320is)
2004 Corvette Z06 Commemorative Edition