Do Dishwashers Heat the Water Or Use Hot Water?

Dishwashers are a godsend when you have a hectic schedule. Anyone who has ever washed dishes by hand would agree that dishwashers save us a lot of time and energy. Have you ever been curious about how dishwashers function and whether they heat the water or use hot water from the kitchen’s pipeline?

Most dishwashers have a built-in heating system that heats the water, whereas some dishwashers use water from the kitchen pipeline at its current temperature. The water temperature inside the dishwasher usually rises to 130 °F (54 °C) which makes removing stains easier.

Do Dishwashers Heat The Water

The rest of this article will explain how dishwashers function, the three stages of a wash cycle, where dishwashers get their hot water from, and why hot water is essential for washing.

Where Does the Dishwasher Get Its Hot Water From?

Dishwashers get their hot water from a small basin at the bottom where the water is pumped. The water pumped in can be either hot or cold, depending on which supply line it is connected with. The internal heating system within the dishwasher heats the water if connected to the cold water line.

If it is connected to the hot water line, the interior heating system can further heat the water to the desired temperature, usually up to 130°F (54 °C).

A dishwasher connected to a cold water line that uses an internal heating system is more energy-efficient.

The internal heating system uses less energy than the heater connected to the hot water line.

However, not all dishwashers come with a built-in heating system.

Some of them use the water from the kitchen at its current temperature.

If the water is cold and there is no built-in heating system, the dishwasher pumps in the cold water and uses it as it is.

Why Do Dishwashers Heat the Water?

Do Dishwashers Heat The Water

Dishwashers heat the water to allow it to easily remove grease and oil. The temperature makes the detergent more effective and helps in breaking down the food particles. The hot water helps sanitize the dishes properly.

If the water is not hot, it can leave behind the remnants of the detergent or food particle which is why cold water is not that effective when killing the germs on the dishes.

If you see remnants of food stains or detergent on your dishes after the cycle is complete, this could be due to a faulty heating system in the dishwasher that requires fixing.

Stages of the Dishwasher’s Wash Cycle

Do Dishwashers Heat The Water

A dishwasher cycle goes through three main stages, each of which is crucial to ensure the best possible cleaning for your dishes.

The Pre-Wash Stage

The water supply line in your house is connected to the water inlet valve, which allows the water to enter inside the dishwasher.

The water gets pumped into a basin located at the bottom, where the heating elements heat the water.

This heated water is sprayed during the pre-wash cycle and helps loosen the food particles on the dishes.

Some dishwashers have an additional slot to add detergent for the pre-wash. If you add the detergent, it gets mixed with the sprayed water.

The pre-wash cycle lasts only a couple of minutes, but every brand and model takes a different time. The water from pre-wash gets drained out, and new water is pumped in for the next stage.

The Main Washing Stage

The freshly pumped water is similarly heated. This heated water gets mixed with the detergent, and this mixture is sprayed inside thoroughly through the multiple spray arms.

The circulation motor circulates water within the dishwasher. This water clears the stain from the dishes and the food particles get trapped inside a filter.

The sprayed water gets collected in the basin again, where it is filtered and heated.

This cycle repeats itself. The heater gets turned off once the desired temperature is reached.

The Rinsing Stage

All the dirty water from the main washing stage gets discharged out of the drain.

Clean water is pumped in, and the same heating, spraying, and filtering process begins.

The water used for rinsing is then drained. The dishes get dried using hot air.

This is why dishes are usually warm if you touch them immediately after the cycle is complete.

Most dishwashers use four gallons of water (15 liters) or less for all three stages combined, which is much less than the 20 gallons (75 liters) of water used if they are hand washed.

The average time for the entire dishwashing process can take anywhere between one and a half to four hours depending on how dirty your dishes are.

If you want to see yourself what is happening inside a dishwasher check the video below:


Dishwashers heat water using heating elements that are internally located.

Hot water allows easy removal of stains. However, some dishwashers don’t have heating elements and use the water from the kitchen’s supply line at whatever temperature it is.

Whether your dishwasher has a heating element depends on the model and brand you are using.
