The primary function, being waterproof, doesn't work

I have new cats adjusting to the house and one of them has peed on the guest bed. I thought a waterproof sheet would prevent future problems except that this wasn't remotely waterproof. Luckily for me I had layered enough things under the sheet just in case an the urine was stopped before it reached the mattress. Otherwise it's fine. It's soft and quiet enough, the elastic is strong and it fits securely. Unfortunately it's completely useless for its purchased function.