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Do Dishwashers Use Hot Water?

A photo of an opened dishwasher with some plates and utensils inside,

Yes, as a matter of fact, they do.

I answered the above question, relieved that at least it wasn’t what I thought he had been asking.  

While Sonny and I were alone doing the dishes, the little man gave me a scare with one of what I call Sonny’s Half-Phishing Questions. Which usually goes something like this..…

“So, dad, do they?” Sonny suddenly asked.

“Do they, what son?” I inquired, a little afraid of where the question was heading. 

“Come on dad, you of all people should know very well if they do, so do they?” Sonny persisted, a naughty grin on his face.

“Well, they might and might not, son, and we will never know until I know who ‘THEY’ are, will we?” I fired back, ready to play Sonny’s little mind game.

Realizing that I could also play his game, Sonny backed down.

“Alright, alright dad, do dishwashers use hot water?”

Happy that I had worn this round, I proceeded to explain.

1. The benefits of hot water in dishwashing

Close up photo of an opened dishwasher with hot steam from the inside.

Many people spend a lot of time cleaning their dishes after a meal-especially when they have a large family. However, thanks to dishwashers, the process is now so much easier. But do dishwashers necessarily have to use hot water?

The answer is yes, they do especially if you want not only to keep your dishes clean but bacteria-free as well.

Dirty dishes are, by their very nature, usually greasy and grimy. Such dishes are not so easy to wash-either by hand or by dishwasher. Unless, of course, you use hot water.

Hot dishwasher water makes cleaning oily residue and grime easier and more effective. Cold water, on the other hand, takes longer and does not clean as effectively-it often leaves residue behind.

Unlike manual dishwashing, which largely depends on physical scrubbing to remove the dirt and grime, a mechanical dishwasher “cleans by spraying hot water, typically between 45 and 75 °C (110 and 170 °F), at the dishes, with lower temperatures used for delicate items.”

As such, when it comes to a dishwasher, hot water is used to wash dishes. Hot water increases the effectiveness of the dishwasher by dissolving grease and grime faster and washing away food particles better.

The more you use hot water in your dishwasher, the less you will use electricity and water. Hot water is always more effective than cold water for cleaning dishes.

Most importantly, there is “the risk of incubating bacteria colonies, particularly Legionella, in water that is not hot enough to kill them. Such a risk is potentially life-threatening but can be balanced by setting the water heater’s thermostat to 55 °C (131 °F).” This usually ensures that bacteria and similar are killed and the dishes disinfected.  

The European Guidelines for Control and Prevention of Travel Associated Legionnaires’ Disease, for instance, recommends that hot water be stored at 60 °C (140 °F) and be distributed so that a temperature of at least 50 °C (122 °F) and preferably 55 °C (131 °F) is achieved within one minute at points of use.

Given the importance of using hot water for hygienic purposes, you will find that it is recommended that dishwashers have “a water temperature within a range of 57–60 °C (135–140 °F) for optimum cleaning.

“Such temperatures not only effectively clean your dishes, but they also easily rinse and disinfect your dishes, as they leave “dishes hot, making the water on their dry up more quickly.”

Related: How Much Water do Dishwashers Use?

 2. How then do dishwashers get their essential hot water?

Close up photo of the dishwasher's interior with kitchenwares being steamed.

In view of the necessity and effectiveness of hot water in the dishwashing process, dishwashers ensure that one way or another, they get the essential hot water they need.

In most cases, how they get their hot water or whether they should be connected to a hot or cold water source depends on the type of brand they are.

The THREE main types of dishwashers are the….

Hot Water Connect

It is always advisable to first ask and confirm from your dishwasher’s dealer or read its manual for connection instructions before purchasing or connecting it.

Older model dishwashers are usually hot water connected because they originally were manufactured without an internal heating element. As a result, they can only be connected to a hot water supply.

Examples of some hot water connect dishwasher brands are: Whirlpool, Kitchenaid, Hotpoint, Kenmore, Lamona, Danby, Frigidaire, General Electric, and Maytag.

However, do not connect your dishwasher to a hot water source with an uncontrollable temperature exceeding 149 degrees Fahrenheit. 

Temperatures above 149 are considered dangerous. This is because tank temperatures above 60 °C (140 °F) may produce limescale deposits which could later harbor bacteria in the water tank. Higher temperatures may also increase the etching of glassware in the dishwasher.

Cold Water Connect

Close up photo of some dishes and kitchenware being washed with coldwater.

Again, it is always advisable to first ask and confirm from your dishwasher’s dealer or read its manual for connection instructions before purchasing or connecting it.

Unlike hot water, cold water connects dishwashers and comes with an internal heater or heating element- a relatively recent technological development in dishwashers. In such cases, “the internal heater will reach the required temperature on its own.”

Examples of some cold water connect dishwasher brands are: Samsung, Defy, Ikea, Ariston, Fisher and Paykel, and Beko.

Cold and/or Hot Water Connect

As their name suggests, these are dishwashers that can be connected to either both hot and/or cold water supplies simultaneously.

They are the latest in dishwasher innovation and come equipped with two inlet hoses as well as an internal heating element. Depending on your circumstances, you can connect to either a cold or hot or both water lines.

Examples of some cold and/or hot water connect dishwasher brands are: Bosch, Dishlex, Asko, Electrolux, Kenwood, Hisense, AEG, Bloomberg, and LG.