The water level has to be high enough to suck it into your engine. not rain or snow, but standing water. Your engine can burn off quite a bit of injested water, it's actually good for it, but when the water taken in outweighs the air, your going to hydrolock. The compression ratio on your car means, the amount of air taken in on the intake, and the compressed by the piston. FYI, water does not tend to compress very easily, voil'a, blown motor.