Mattress encasements, including waterproof mattress pads, are the easiest way to protect the manufacturer’s warranty on your mattress. Should a problem arise with your mattress, it must be free of stains in order to qualify for a warranty exchange or repair. Aside from keeping your mattress free of stains, many mattress protectors have the ability to keep dust mites, bed bugs, and other unwanted guests out of your new mattress and away from your skin.