I haven't always blown out the water in my exhaust but one time I disconnected the coil and turned the engine over to seat the impeller correctly (I don't pull mine) and quite a bit of water came out. I now raise the bow and turn the engine over (coil disconnected) for about 3-4 seconds. I have never had a problem before I started to blow the water out so I don't think there is much water that stays in.