I bought this as one component of my mattress protection system. I have not read reviews of ANY mattress protector that said they were completely waterproof, and I have not tested that claim on this cover. I put this cover on a new mattress, and then another supposedly waterproof mattress encasement over it and the mattress. The hope is that should the mattress be subjected to a moisture accident, that having both will protect the mattress. I saw a good suggestion from another reviewer, however, to use a vinyl shower curtain to really protect a mattress, and if I had an incontinent sleeper using it, I would have put a vinyl shower curtain underneath this mattress cover, THEN encased the whole thing. I put a regular washable quilted mattress pad on top of the encasement to eliminate the hot, "plasticky" feeling the waterproofing can cause. Otherwise, this seemed to be a quality product that met my expectations. Be aware that it is a COVER, not an ENCASEMENT.