Cleaning a mattress is a difficult task. That's why the mattress pad was invented. It adds another layer of protection between you and your mattress since often times, sheets are not enough to keep the mattress clean. Many mattress pads are made from the synthetic fiber called polyester, which is a washable material. It is also very durable and will last years and years. You should clean your polyester fiber mattress every few months.
Look at the washing instructions on the tag. You should still have your tag attached to the mattress pad. The safest way to wash your mattress pad is according to the manufacturer's instructions.
Pre-treat any stains. Just as you would for any other fabric, you can use a product like Shout to pre-treat stains.
Machine wash the pad in cold water. Most polyester fiber mattress pads will say they are machine washable. Unfortunately, many do not say in what water temperature. Also, some say to wash in hot water. But washing in cold water will keep your mattress pad from shrinking over time. You can use any detergent, but do not use bleach with chlorine as this may cause damage.
Tumble dry the pad on low heat. Usually the tag will say you can tumble dry. Do so on a low setting to prevent shrinkage or stretching of the elastic. If you pad is larger than a twin size, you can add a couple of tennis balls into the dryer so the pad does not wrap into itself and form a ball. The middle does not easily dry this way.
Hang the pad to dry in the sun. If you washed your pad in cold water and are worried about dust mites or killing off bacteria from a bodily fluids like urine, then you can hang your polyester fiber mattress pad in the sun. Flip it over half way through the drying process.