Most of the time the mattress cover performs its mattress-protecting job. Periodically, it's necessary to launder the mattress cover. A mattress cover should be washed and dried whenever it has been saturated with spills or other fluids. The North Carolina Cooperative Extension Service website recommends applying a pre-wash product to soiled areas on a mattress cover, and placing white tennis balls in the dryer with it to help prevent the mattress pad from bunching up. With a large enough washer and drier and basic laundry products, you can keep your mattress cover clean.
Remove the mattress cover and check the inside seams for a manufacturer's care tag. It's usually in a corner, sewn into a seam. Check for the recommended washing temperature.
Apply stain remover or a pre-wash product, such as an oxygen cleaner for laundry, on any stained or soiled areas of the mattress cover. If in doubt about how to treat a stain, refer to a stain removal guide. The University of Illinois Extension website provides an alphabetized list of stain treatments. Follow the product instructions and leave the laundry product on the mattress cover for the required length of time, usually 15 to 30 minutes.
Check that the stain removal has worked by rubbing the areas of the fabric together with your hands. If not, rinse the area in cold water, apply more product, and wait again. Laundering and drying the mattress cover will cause stains to set, so remove the stains as much as possible before washing the mattress cover.
Put the mattress cover in a large home washing machine or a commercial washer. Add laundry detergent. Add more oxygen cleaner, if desired. Wash on the warmest setting allowed by the manufacturer's care tag. If no care information is available for the mattress cover, wash it in cold water to avoid the risk of shrinkage. A mattress cover that shrinks will no longer fit the mattress.
Place four white tennis balls in the dryer with the mattress cover. Dry the mattress cover on a medium heat setting to reduce the risk of shrinkage, unless the care instructions direct otherwise.