I put drain holes in the lowest location I could at the bottom. I also carry duct tape in the plane. If I wash the plane or anticipate rain, I place duct tape over the spots where water can get in. I have closed off the pass through in the horizontal access panel with Food industry easy-cut strip brushes that you can get from McMaster-Carr. I have not washed the plane since I put those on so I don't really know if it really helps with keeping the water out but I suspect it does unless I put the stream from the hose directly at it.