"Your kitchen sponges and dishrags are spreading germs! Did you know that just putting a sponge through the dishwasher, even with the hottest temperature setting, doesnt kill much of the bacteria that sponges collect when used to wipe down the counter top and cutting board?" http://www.pushback.com/Wattenburg/health/ This is because the pathogens in your sponge/dish rag actually surround themselves with a relatively impermeable 'shell." "His studies have shown that if they aren't sent packing quickly, the microbes produce an organic goo with threadlike tendrils "that literally cements the cells to the surface." This allows them to weather the elements--fast-flowing sprays of water, a little rubbing, or a weak detergent solution. Eventually, unrelated families of microbes move in. The resulting cosmopolitan community forms biofilms that further protect its inhabitants." http://www.sciencenews.org/sn_arch/9_14_96/bob2.htm There is an easy way to kill most of the bacteria though. Dampen the sponge with plain water, and then put it in the microwave for a minute or two (long enough to generate steam). The boiling off of the water will kill a significant portion of the bacteria and lessen the numbers of bacteria being spread the next time you use the sponge to clean something. Do this every three days. BTW that plastic cutting board? It harbors bacteria as well. Wood cutting boards have been found to significantly reduce pathogens. Wood cutting boards actually 'suck' pathogens down inside the wood fiber where they do not multiply and eventually die. Plastic and glass cutting boards allow bacteria to persist. http://faculty.vetmed.ucdavis.edu/faculty/docliver/Research/cuttingboard.htm