Average dishwashers use eight to fourteen gallons of water for a complete wash cycle and require a water temperature of 140 F for optimum cleaning. 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. 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. In this case, your energy costs could be higher than with the standard-capacity dishwasher. Washing machines do not require a minimum temperature for optimum cleaning. Make sure you follow the cold water washing instructions for your particular laundry detergent. Inefficient washing machines can cost three times as much to operate as efficient machines.