To clean a sponge in the microwave, moisten the sponge and place it in the microwave on high power for four minutes. Sponges with plastic scrubbers are microwaveable, but sponges with metal are not. Allow the sponge to cool before removing it.
Microwaving sponges is a quick and effective cleaning method. Research shows that four minutes in the microwave kills all the germs the sponge collects, including E.coli, salmonella, mold and other bacteria spores that sponges can collect in the kitchen and bathroom. Even new sponges can quickly collect harmful germs after a short period of use. WebMD recommends that sponges be cleaned in the microwave every other day.