Most people know they need to sanitize the bathroom regularly but might not realize just how many germs are lingering in the kitchen. Kitchens are home to a number of common bacteria, including "E.coli, salmonella, shigella, campylobacter, norovirus and hepatitis A," according to infectious disease specialist Dr. Susan Rehm.

Sponges “were proven to represent the biggest reservoirs of active bacteria in the whole house,” according to a recent study from Scientific Reports. Bacteria can multiply quickly in a sponge because it gets wet and stays moist, and, as Dr. Charles Gerba points out, “Most E. coli and other fecal-based bacteria in the average home are on a sponge or cleaning cloth."

Although microwaving a sponge can kill some bacteria, it can leave strong strains behind that can cause disease. Even if you clean your sponge regularly, bacteria can stick around and make it just as dirty as before, which is why it's best to replace the sponge.