B2Bomber: thanks for the comments. I go your point. So it really means that the paint protect does not prevent from getting my car a water mark. However, it contradicts from what i read before.

Anyway, it was rainy season since June or July and i have been doing the my detailing process before and it was water mark free. I have left my car with water rains on it for several times. Besides, you can't always keep your car dry, do you? Like if you parked your car in the office garage after a rainy day, i dont have time to dry it off. Or just even after you parked your car in your garage and your too tired, right?

If that is the case, i should have not been too confident with the paint protect and just stick with the process that i have been doing. I was in a assumption that the paint protect can deal with those water marks with no problem, but i was wrong.