The mattress pad, although it is not waterproof and will not protect against heavy leaks, is the best way to protect the mattress from small spills, as well as dirt and oils from the body. If there is a possibility that your mattress may need protection from heavy spills then we would recommend also purchasing a wool moisture pad. {Product update, November 2013, we now also offer a machine washable wool quilted mattress pad which works similar to a cotton mattress pad}