The USDA found that cleaning sponges in the dishwasher is nearly as effective at killing bacteria as microwaving them, and is also a better option for sponges with metal scrubbing pads or abrasive components. They discovered that sanitizing a sponge in the dishwasher can kill 99.9998% of bacteria, simply by running the sponge through a hot water dishwasher cycle with a drying cycle. Reference your dishwasher owner’s manual for more information about what can and can’t go in your dishwasher.