Well i been on the net looking for a solution and nothing seems to work on my beautiful water stains on my windows (vinegar, autoglym polish, rainx stong cleaning stuff, lemon juice, razor, toothpaste, ultimate compound etc...) I tried everything, then i saw an old kitten cutting compound in the shed n tried it on a MF pad + sprayed some quick detailer as lub and started rubbing and it all vanished, bit of elbow grease (not to much pressure we don't want to scratch it ) and it was gone, but gotta be careful to use clean MF cloth to wipe out and not let dry, kinda barbarian but works