The Maximum Discharge Temp for Dishwashers

Maximum Temperature

• Set your residential dishwasher’s discharge temperature between 140 and 160 degrees Fahrenheit, states MasterPlumbers.com. Although certain dishwasher manufacturers may recommend a lower discharge temperature, the U.S. Department of Energy recommends a discharge water temperature of about 140 degrees Fahrenheit for dishwashers, which it claims on its website is ideal for cleaning.

Proper Cleaning and Sanitation

• Although 160 degrees Fahrenheit is the maximum discharge water temperature for a dishwasher, a temperature of anything less than 140 degrees Fahrenheit won’t completely eliminate germs and bacteria on dishes. Although you may think that reducing the discharge temperature may decrease your utility bill, it may actually increase the cost if you have to rewash dishes because the dishwasher didn’t get them entirely clean in one cycle.

Avoid Damaging Dishes

• Setting your home’s hot water heater to discharge water to your dishwasher at a temperature anything above 160 degrees Fahrenheit can damage dishes. When very hot water mixes with dishwasher detergent it can leave a white film on dishes and glassware that can be difficult or impossible to remove. Furthermore, certain dishes, such as those made of plastic and rubber, can warp or curl if they’re washed in water that’s too hot.

Considerations

• Since kitchen and bathroom faucets have a lower maximum discharge water temperature of about 100 degrees Fahrenheit compared to dishwashers and washing machines at 160 degrees Fahrenheit, you may want to install a tempering valve to regulate the supply of water to various water outlets in your home. The valve will automatically adjust the water temperature supplied to kitchen and bathroom outlets to 100 degrees Fahrenheit or less -- whatever temperature you choose -- by mixing hot water with cold to get the right temperature. This way, you don’t have to choose one discharge water temperature for all of your water outlets and appliances. In addition, you may also want to install a balancing valve to your kitchen and bathroom faucets that would prevent you from getting scalded when using hot water for washing when another household member starts the dishwasher or flushes a toilet, creating a sudden water pressure drop that would otherwise impact the temperature at other water outlets in your home.