Rinse the sponge thoroughly with hot water
Wring out excess water
Microwave a damp sponge for 1 to 2 minutes
Or soak the sponge in a bleach solution for 5 minutes
Or run the sponge through a dishwasher on a hot cycle
Rinse the sponge again after sanitizing
Wring it out completely
Let it air-dry in a clean, open area
Replace the sponge regularly if it smells bad or looks worn