 One teaspoon of bleach in a cup of water for a minute or microwave it, sopping wet for a minute. A dry sponge can catch on fire, by the way. And be sure to replace it often. Ideally, every week or switch to dishcloths that can be used for a day and then be laundered. The final item we're going to talk about at 8.52 this morning, wash your grocery bags.