Learn more about optimal water temperature for clean dishes.
Do Dishwashers Use Up Your Homes’ Hot Water?
Updated on May 21, 2024
All brands of dishwashers need really hot water to work their best. In my 30 years of appliance repair, I’ve seen many dishwashers not cleaning well and not melting the soap because the water wasn’t heating properly.
The 120-degree water from your home’s water heater generally isn’t hot enough for your dishwasher to do its job. That’s why most dishwaters boost that water’s temperature to 160 degrees, high enough to kill all pathogens and melt all your dishwasher soap.
If you open your dishwasher door 30 minutes into the cycle, you should see a big plume of steam billowing out. If not, something’s wrong with your dishwasher’s heating system.
The most common reason for a dishwasher not heating properly is the water inlet valve not letting in enough water to activate the heater. At 30 minutes into the cycle, if you open the door you should see water high enough to touch the heating element near the bottom of the dishwasher.
Some dishwashers, like Bosch and Miele, feature hidden heating elements. The water level on Bosch dishwashers should reach the top of the round plastic filter handle. On Miele dishwashers, it should reach the bottom of the white plastic filter handle.
When a dishwasher’s fill valve doesn’t let in the right amount of water, the water won’t heat enough to clean the dishes. Replacing the fill valve could solve this problem.
Other possible causes of poor water heating:
- Controller heater relay malfunction;
- Worn out or melted heating element;
- Blown heating circuit Hi-limit (fuse);
- Broken or rodent-chewed wire to heating element.
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How Hot Do Dishwashers Get?
About 160 degrees, as mentioned above. During the drying cycle the heating element can go as high as 170 degrees. At that temperature, some plastic items near the heating element can melt. Best to place plastic items on the top rack.
Can You Use Your Dishwasher Without Hot Water?
Yes, but it’s not optimal. If your dishwasher takes in cold water, it can still clean the dishes, but it will take much longer to finish the cycle. If the situation continues for many cycles, the heating element may wear out prematurely.
Does a Dishwasher Use Less Hot Water Than Washing Dishes by Hand?
Yes. Hand washing also uses 120-degree water, which isn’t enough to kill pathogens that can cause food poisoning.
How Long Do Dishwashers Run?
About 90 minutes, including the drying cycle. If you run your kitchen sink hot water for five minutes before starting your dishwasher, your run time should be shorter, because it will take less time for your dishwasher to heat up the water.
Sanitize cycles take longer because it takes longer for the water to reach the higher temperatures required.
