Cleaning out the dishwasher on a regular basis helps to maintain efficiency and to ensure that dishes are truly clean. Plain white vinegar is a safe, general-purpose cleaner for all parts of the dishwasher's interior and drain system, but a complete cleaning process includes scrubbing the dishwasher tub and cleaning all filters before cycling the vinegar through the system.
Remove the lower rack from the dishwasher. Clean the dishwasher's filters as directed by the manufacturer. Many models have a filter screen in the center of the tub's floor, as well as one or more secondary filters under the screen. Consult your owners manual for proper filter removal and cleaning procedures.
Fill a bucket with hot water and add a suitable amount of dish soap to create a sudsy cleaning solution.
Dip a toothbrush or nylon-bristle cleaning brush into the soap-and-water solution and scrub along all cracks and crevices in the dishwasher tub and the interior surfaces of the door. This helps loosen up any stuck-on food particles, debris, grease or mineral buildup that occurs with normal use. Wipe down all surfaces inside the dishwasher with a sponge.
Fill a dishwasher-safe glass or cup (a glass measuring cup works well) with white vinegar and place it upright at the center of the top rack of the dishwasher. Reinstall the lower rack. Run the dishwasher on its hottest and longest cycle (such as the "sanitizing" cycle). The dishwasher should be empty except for the vinegar-filled container. Let the dishwasher complete the full cycle, then open the door and allow the interior to air-dry before loading and running the dishwasher as usual.