Sponges do not have a very long life time, so if they start to fall apart, toss them. In the meantime, you should sanitize a sponge to prevent E.coli, salmonella, and other kitchen bacteria at LEAST once a week! The best way is to soak in a mixture of 3 tablespoons of bleach and a quart of water for 5 minutes. You can do several at once this way. Other ways are to microwave a wet sponge for 2 minutes or in the dishwasher (top rack) in a cycle that uses the heated dry option.