How Do Dishwashers Work? (You Didn’t EXPECT This!)

Dishwashing was always a hard chore for everyone. Except maybe for Agatha Christie, who came up with plot ideas as she did the dishes! That’s why there have been many attempts to automate the process since the olden days. 

The first successful dishwashing machine came out in 1886, thanks to the wonderful invention patented by Josephine Cochrane. This was also the beginning of a whole new line of home appliances, that we all know: KitchenAid. 


These time and effort-saving machines soon became an integral part of every household. So, exactly how do dishwashers work? 

Read on to know all the details, in a simple and fun way! 

So How Exactly Do Dishwashers Work?

Most people are amazed to know that new-age dishwashers aren’t drastically different from the first models of the last century. That’s because these machines are primarily simple electro-mechanical systems. 

Manufacturers could add frills, bells, and whistles, but the basic designs aren’t too complicated.  

The General Idea

The idea is to spray the dirty dishes and dinnerware with water, and let it soak for a bit, then add detergent. This washing cycle is followed by a thorough rinse. Some machines stop at that, while others add a drying cycle. 

How Are Dishwashers Installed

Dishwashers are often installed below the counter. There, they get their input water from the kitchen line and direct their drainage to the sink kitchen drain. It’s essential to connect the machine to a 120 V supply, and make sure it’s well-grounded. 

There’s another option, which is the over-the-counter portable dishwasher. These models are often smaller in size, and they’re the preferred choice for renters or in vacation homes. These machines hook up to the kitchen faucet and drain the used water in the sink. 

Domestic vs. Commercial Dishwashers

Domestic dishwashers are made to suit the needs of small, medium-sized, and large households. The primary goal is to clean up the dishes thoroughly and quietly. Cycle times do not matter much, as typically, the services of a dishwasher are only needed once or twice a day.

On the other hand, commercial dishwashers need to have much higher capacities and much shorter cycle times. Additionally, the dinnerware and cutlery have to be sterilized and sanitized, not just washed. These are strict requirements, but they’re necessary to avoid cross-infection.   

The 4 Cycles of Dishwashing 

Most dishwashers employ four cycles to clean up the dishes. Modern dishwashers could include extra programs for a quick rinse, a soaking cycle, or an economy wash. These are often abridged cycles, but they follow the same principles as the main washing cycles. 

The Filling-Up Cycle 

The cycle starts as soon as the program is specified, and the ON button is pressed. There are a few checks that the machine does at first. These are; checking that the door is firmly locked, that there’s detergent in the drawer, and that the basin isn’t already flooded. 

An OK signal activates a water valve to let in a specific amount of water. Simultaneously, the heating element is also turned on, and the detergent drawer opens up. The water can reach a temperature of up to 155 degrees Fahrenheit. 

The Cleaning Cycle

Once the water is good and ready, a pump pushes the water up into the spray arms. The powerful jets of water hit all the plates and cutlery from every angle. This way, the food, and grease slide off the dinnerware.

The used water then drains out of the basin, aided by the guidance of another pump. Some machines contain filters to catch the food debris before letting it into the drain hose. Others contain little grinders that shred the organic debris into tiny pieces.  

The Rinsing Cycle 

The rinsing cycle is pretty similar to the cleaning cycle. But this time, instead of the detergent, rinse-aid is released into the basin. This helps in keeping the glassware shiny and free from any smudges. 

The rinsing water then drains off just like in the cleaning cycle. 

The Drying Cycle 

The drying cycle is optional, but most people like to run it. The plates and cutlery are more hygienic and usable when they aren’t wet or humid. 

The heating element is activated once more, but this time, it only warms up the air. The circulating hot air then dries up the contents of the dishwasher. 

Why Do Dishwashers Have a Bunch of Sensors?  

A lot can go wrong in machines that don’t have monitoring and control systems. The various cycles of filling up water, heating the water, and draining the water could wreak havoc inside the dishwasher if they last too long, or if they don’t start at all. 

Here are the basic sensors that you’d commonly find in a dishwasher: 

  • A door latch sensor to make sure the door is properly closed. 
  • A timer circuit regulates cycle duration. 
  • A sensor to activate the detergent dispenser.  
  • A thermostat detects and controls water temperature to prevent overheating. 
  • Another thermostat detects and controls internal air temperature. 
  • A float and water level detector keep the dishwasher from becoming flooded with water. 

It’s worth noting that these sensors have a specific lifespan, and they eventually stop working. This is one of the primary causes of the dishwasher’s erratic operation and error messages. Thus, it’s worthwhile to check the sensors first if something is off with the machine.

Additionally, the above-mentioned sensors are the basic monitors and controllers. This doesn’t mean that they’re the only ones in all machines. More advanced and sophisticated dishwashers would have more sensors to optimize the system even more. 

For example, there’s a sensor for water clarity, which measures the cleanliness of the drained rinsing water. If it still contains dirt, then the washing cycle wasn’t too effective. Then, the machine runs an extended cleaning cycle to correct the matter. 

That’s not even the highest tech currently available, there’s a lot more! 


Understanding what’s under the hood of the appliances around us is always informative. But on top of that, there are many benefits to knowing how these machines work. It helps us in getting the most out of them, maintaining them properly, and even fixing them if needed. 

So, if you were wondering how do dishwashers work? Now you’re very much the expert!