When selecting a professional dishwasher for a catering operation, it is important to choose a model considering the size of the dishes, a parameter referred to as the "maximum plate diameter." The plates actually used in the operation must match this parameter. The basket size is a parameter determining the number of plates washed during one washing cycle. The placement of the professional dishwasher will indicate whether a model with a drain pump is needed, or if gravity drainage will suffice. If the dishwasher is connected to a drain higher than the dishwasher's waste outlet, a drain pump is necessary.