Set the washing machine controls to the hottest water temperature and the longest agitation length.
Turn on the washer and, while it is filling, add 1 cup Clorox.
Stop the machine once the tub is full and. while wearing latex gloves, dip the sponge into the hot Clorox water.
Wipe down the inside cover and the area above the washer drum.
Close the washing machine lid and allow the machine to run through all cycles, the same as if you were washing a load of clothes.
Change the setting to "Rinse" only and allow the machine to run through an extra rinse cycle. All the Clorox will now be removed, and your washing machine will be clean and sanitized.