But setting your water heater so high could result in excessive standby heat loss. This type of heat loss occurs because water is constantly heated in the storage tank, even when no hot water is used. Some dishwashers have built-in boosters that will automatically raise the water temperature, while others require manual selection before the wash cycle begins. Reducing the water heater temperature is not advisable, however, if your dishwasher does not have a booster heater. Another feature that reduces hot water use in dishwashers is the availability of cycle selections.
Shorter cycles require less water, thereby reducing the energy cost.
The most efficient dishwasher currently on the market can cost half as much to operate as the most inefficient model.