A dishwasher is provided which uses a combined circulation/drain pump and an improved filtering system to enhance cleaning capability. The circulation section of the pump provides pressurization and supplies wash water to a spray arm of the dishwasher, while the drain section discharges the wash water. This single pump reduces space requirements, as well as manufacturing costs. A two stage filtration system may be used in the water collection area of the dishwasher to filter out unwanted material, and a third filter may further filter wash water prior to recirculation. Self cleansing mechanisms associated with each of the filters may be used to keep the filters free from obstructions and allow for the unobstructed flow and discharge of wash water.