Mildew thrives in warm, moist places, especially in the interior of a dishwasher. One way to remove mildew from a dishwasher is to clean it with bleach. This is a quick process.
Make a bleach and water mixture
Mix 1 cup of bleach into 1 gallon of water. Wear gloves and make sure ventilation is adequate when preparing the mixture. Avoid spilling the mixture on clothing since the bleach will remove color.
Scrub the dishwasher with the mixture
Use a stiff brush to apply the bleach mixture to the interior of the dishwasher. For small, hard to reach areas, use a toothbrush to scrub. Scrub the racks and the door, paying particular attention to the area underneath the seal as mildew often likes to hide there.
Run the dishwasher
Without placing anything in it, run the dishwasher through a cycle. This will rinse out any bleach residue, making the dishwasher safe to run dishes through once again.
Scrub the remaining stains
Inspect the dishwasher for any remaining mildew stains. Tackle these difficult stains by scrubbing the area with a damp rag and mild scouring powder. Inspect the dishwasher regularly for any signs of mildew. Repeat the entire process if it reappears.