Helps, but definitely  not water proof.  Resistant would be a better description. The inside cushion came in a heavy duty plastic bag so I kept that on for added protection  because my dog leaks when she sleeps. I also added a 
leak guard  mattress cover to the top of the dog bed so that I don't have to wash the dog bed cover as much I can just take the mattress protector off which is easier than removing and redoing the dog bed cover each time . But it is washable.