If you don’t toss yours weekly like Rach says she does, you have a couple of other options. You can have two sponges on rotation in your kitchen. After you have used one sponge, put it in the top rack of your dishwasher when you are going to run it. Another way to get your sponge really clean is to soak it in vinegar and put the sponge into the microwave for two minutes. In addition to cleaning the sponge, the steam from the sponge will help release the gunk from the inside of the microwave and you can give your microwave a quick wipe down as well.