The tub gasket, also known as the door gasket runs along the perimeter of your dishwasher basin and creates a seal that prevents water from leaking out when the tub is full. If you notice water on the floor after you run your dishwasher, it may be an indication that the gasket is loose or damaged. If your door gasket is damaged, it will need to be replaced. To replace the gasket, simply pull the old gasket out of the groove it rests in, and press the new gasket into place. This part is made of black rubber and is sold individually.