Microwave: The microwave was one of the next most effective ways to clean a sponge, zapping 99.9% of germs. Do this by saturating the sponge in water (we used 1/4 cup for scrub sponges and 1/2 cup for cellulose), putting the sponge in the microwave, then heating it on high for one minute (scrub) or two minutes (cellulose).
Dishwasher: The dishwasher also killed 99.9% of germs. To use, add your sponge to a regular dishwasher load, using the “heated dry” setting.
Vinegar: This method eliminated 99.6% of bacteria. All you have to do is soak your sponge in full-strength vinegar for five minutes, then rinse.