How long should I keep a dish sponge?
Sponges can trap all kinds of bacteria, and since they stay moist too, they can be a real hazard. However, some studies indicate they can be sterilized by putting them in the microwave. To read how to do that, click here. Other sources indicate that running your sponge through a hot dishwasher cycle kills about 99% of bacteria too. If you forget to sanitize your sponge or don’t have time to sanitize, plan to replace your sponges regularly!
I squirt a little bleach on mine about once a week or so,
followed with a rinse in plain water.