NSF International, an independent public health and safety organization, found that the kitchen, not the bathroom, is the germiest room in most homes. The sponge earns the infamous title of germiest kitchen item. Sponges are moist and have many crevices for germs like coliform (including salmonella and E. coli) to rapidly form. You can spread germs across your kitchen when you use a bacteria-laden sponge to wipe countertops. The NSF recommends replacing kitchen sponges approximately every two weeks. Sanitize your sponge daily by placing it in the microwave for a minute or two or by running it through the dishwasher.