What's good for your hands must also be good for your clothes, right? Not so fast. For one thing, your washing machine receives dozens of garments every time you do laundry. That means it must clean an area far bigger than your hands. And don't think a dirty T-shirt carries fewer bacteria than skin. According to germ guru Charles Gerba, a load of undergarments transfers about 500 million E. coli bacteria to the machine [source: Roberson]. If you're using a front-loading machine, which can't always expel all of the water from one wash cycle, these bacteria take a leisurely swim until the next load arrives. In essence, you're washing dirty clothes with contaminated water.
A better solution (aside from throwing away clothes after each use and starting over with new ones) is to wash whites first in chlorine bleach. Follow this up with a load of underwear, using hot water and color-safe bleach substitute. Once a month, you should add bleach and run an empty cycle. This sanitizes your machine and helps to reduce the number of bacteria found on your clothes.