1. Microwave
The microwave is the most effective, zapping 99.9% of germs. Do this by putting the sponge in the microwave, saturating it in water (we used 1/4 cup for scrub sponges and 1/2 cup for cellulose), then heating it on high for one minute (scrub) or two minutes (cellulose). Allow to cool.
Warning: This only works for non-metal sponges! No metal in microwaves!
2. Dishwasher
The dishwasher also kills 99.9% of germs. To use, add your sponge to a regular dishwasher load, using the “heated dry” setting.
3. Vinegar
This method eliminates 99.6% of bacteria. All you have to do is soak your sponge in full-strength vinegar for five minutes, then rinse.