Your washing machine needs routine cleaning to help keep your clothing clean. When you wash things like dirty kitchen towels and heavily stained clothes, germs and bacteria can linger and grow inside the washing machine. This is even truer if you wash only in cold water. Laundry detergent isn't designed to sanitize, but to clean clothes. To sanitize your washing machine, pour a cup of bleach and run a full wash cycle using hot water with an empty drum.