Well, this product is made with a very thin plastic like substance--so it is probably waterproof. This is such a new purchase for me, that I cannot verify it's durability or waterproof efficacy. I placed it upon a 6 inch mattress...I think it would be a tight squeeze for much more that 8 inches. For the price, I think I have made a good purchase.

Pros: plastic like substance, so probably is waterproof...it has not yet been subjected to a water test by me.
Cons: very thin, durability is questionable