Inside Your Dishwasher: What Really Gets Your Dishes Clean?

Dishwashers are a staple in most households, but most people don’t know, but most people don’t know the science and mechanical workings that go on when the dishwasher door is closed. Dishwashers come in a variety of sizes and styles, from built-in to portable dishwashers, but they all operate in the same way. So, what does happen? How does anything get clean? We’re happy to tell you.

woman loading her dishwasher

Dishwasher Basics


A dishwasher is essentially a machine that cleans and rinses soiled dishes. Users must load the dishwasher, add detergent, set the appropriate cleaning cycles, and switch it on, but the dishwasher does several tasks on its own. Dishwashers usually have a control that allows you to set the amount of time the dishwasher runs for. They also have sensors that detect how much soil is on the dishes, allowing the dishwasher to calculate how much water to use and how long to run the cycle. Most dishwashers offer a “fast wash” cycle that lasts 30 to60 minutes, a “regular” cycle that lasts 90 to 120 minutes, and a “heavy-duty” cycle that can last up to four hours.


The Cycle

an open loaded dishwasher

When you start up the dishwasher, it receives cold water from your home’s water source. The water is then heated to temperatures between 86 and140°F by an electric heating element at the bottom of the machine. That’s far hotter than most people’s washing water, which is one of the reasons dishwashers are more sanitary.


The water is pumped up through the side walls by an electric pump at the bottom of the machine. After bouncing off your plates, the water returns to the machine’s bottom, where it is heated and pumped around the circuit once more. A heated dry is the final stage of a cycle. The same heating element that heats the water during the wash cycle also heats the tub, causing the water to evaporate off the dishes.


Pro Tip: If your dishwasher is connected to your hot water supply, the cycles will run faster as the water doesn’t require as much heating. For the optimal clean every time, dishwashers work best if connected to both your hot and cold water lines.


glasses being washed in a dishwasher

Types of Spray Action


As the water is pumped through the walls, depending on your dishwasher design, it is also being pumped through other cleaning features like:


Lower Spray Arm: This is the main (lower) wash spray arm, placed at the tub’s bottom. This wash arm moves beneath the lower rack, spraying water into both the lower and upper racks.

Power Tower: The tubular-shaped power tower that is affixed to the center of the main wash arm. The power tower telescopes upward above the dishes in the lower rack due to water pressure, resulting in a spray wash from the middle of the tub out of the multi-hole tower. Great for washing the insides of glasses, bowls, and cups.

Middle Spray Arm: The spray arm beneath the upper rack contains downward-facing jets. Water sprays over the lower dishes as the spray arm spins.

Upper Spray Arm: also known as the spray nozzle, sprays water from the dishwasher’s top. The spray action occurs above the upper rack, at the top of the dishwasher. Water is directed downward by the spray arm or nozzle onto things in the upper rack.


Dishwasher Options

open dishwasher with steam coming out

Depending on your dishwasher brand, you might see different settings that affect the standard mechanics of your dishwasher. For instance, a Hi-temp cycle increases the minimum temp for your washer to a minimum of 130°F to cut through grease and baked-on stains.


Dishwasher cycles today are designed to use less water but the cycles will also last longer. A new ENERGY STAR® certified dishwasher consumes less than half the energy of a traditional dishwasher and saves an average of 3,870 gallons of water over its lifetime, which saves you money.

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