The SpongeBath System, touted as the first dual-purpose sponge holder that both cleans and stores your sponge, comes with a holder and a patent-pending concentrated cleaning solution that is said to kill 99.99 percent of odor-causing bacteria (The solution is made with all-natural and food-grade ingredients including citric acid and malic acid.) A quick 10-minute soak gets the job done, although the site suggests letting the sponge soak in the cleaning solution whenever you're not using it.