Dishwashers and methods of control for operation of dishwashers are disclosed. The dishwasher can include one or more racks in a washing compartment for placing used dishes having foreign matter, such as food and drink, and unused dishes having relatively little or no foreign matter and varying washing loads. Operation of the dishwasher can include wash, water drain and supply, and rinse cycles. During the cycles, preheating of a steam generator, water draining and supplying, steam supplying, and water spraying can occur and partially or fully overlap. The dishwasher can reduce excessive washing of dishes having small washing loads and improve power and water consumption.