A water recirculator in a dishwasher supplies water to spray arms for washing dishes and also purifies contaminated water after washing the dishes. The water recirculator includes a sump for holding water, a water supply pump connected to the sump, a guide passage for guiding a portion of the water pumped by the water supply pump to a spray arm in a washing chamber, a pre-filtering unit for purifying a rest of the water pumped by the water pumped by the water supply pump by means of precipitating contaminants included in the water therein, and a main filtering unit for purifying the rest of the water passed through the pre-filtering unit.