A 2008 study sponsored, but not conducted, by Lysol found that 75 percent of kitchen sponges in the United States contained harmful bacteria. Internationally, 90 percent of kitchen sponges and 46 percent of kitchen sinks had high levels of bacteria, meaning more than a count of 100,000 per square centimeter. What exactly do they mean by "harmful bacteria," you ask? We're talking e-coli and salmonella. While they won't likely kill you, you could end up with a nasty bout of diarrhea or other stomach aliments. The same study, which used samples from 20 homes from seven regions around the globe, found that the kitchen sink contained more germs than a flushed toilet bowl.
Children, animals and food are all heavy sources of bacteria, and kitchens see a lot of each in most homes. Dogs running around, food crumbs left on the counter, children touching every surface with their unwashed hands -- it's a virtual playground for bacteria. You wipe up food with your sponge and give it a good rinse, but some of that gravy you spilled will end up staying put and breeding bacteria. Another reason why a toilet is cleaner is because people generally clean them more aggressively than they do a kitchen sink. Toilet bowls are scrubbed with wire brushes using heavy-duty cleaners. Many kitchen sinks are simply rinsed and wiped on a regular basis. This may keep the surface clean, but it does nothing for the bacteria count.
Experts recommend that you wet your kitchen sponge down and pop it into the microwave for two minutes on a regular basis. This will wipe out 99.9 percent of the bacteria currently making a home in your sponge. This method beat out soaking the sponge in either a bleach or all-natural lemon juice solution in a study performed in 2007. And don't feel bad about your cleaning habits; bacteria is always in places you use the most. A 2008 UK study found that your computer keyboard also had more bacteria than the toilet.