How Dishwashers Function

Essentially, a dishwasher is a machine that cleans and rinses your dirty dishes. While humans need to load the dishes, add detergent, choose the correct wash cycle, and start it, the dishwasher takes care of all the cleaning and rinsing by itself. A dishwasher:

Additionally, dishwashers are self-monitoring to ensure everything runs smoothly. A timer (or small computer) controls the duration of each cycle. Sensors check the temperature of both water and air to prevent overheating and protect your dishes. Another sensor can detect if the water level gets too high, triggering the drain function to prevent the dishwasher from overflowing. Some models even include sensors that assess the water's cleanliness. Once the water is clear enough, the dishwasher knows the dishes are clean.

While dishwashers are sealed tight, they don’t actually fill completely with water. Instead, a small basin at the bottom fills up. Heating elements warm the water to as high as 155 degrees Fahrenheit (68 Celsius) while detergent mixes in. Then a pump sends the water upward to the spray arms, where it is forced out and sprayed onto the dirty dishes.

Imagine a garden hose without a nozzle — if you block the end with your thumb, the water comes out with more force. The dishwasher’s jets work on the same idea. The force of the water also causes the spray arms to spin, much like a lawn sprinkler.

After food particles are removed from the dishes, they are either trapped in a filter or broken down into tiny pieces, similar to a garbage disposal. The process of heating the water, spraying it, and allowing it to drain back into the basin below repeats several times.

Once the washing and rinsing are complete, the water drains back into the basin, where the pump pushes the water out of the dishwasher. Depending on the model, the used water is either directed into the pipes beneath your sink or into the garbage disposal.

The last stage of the wash cycle is optional — the drying phase. The heating element at the bottom of the dishwasher warms the air inside to assist in drying the dishes. Some people opt to skip the heated drying to conserve energy.

Dishwashers aren't overly complicated mechanically. In the following section, we’ll explore the key components of a standard dishwasher.

Dishwasher Overview

Here are the key components of a dishwasher:

Control System

The control system is situated inside the door behind the control panel. Most units feature a basic electro-mechanical system where a timer manages the duration of each cycle segment and triggers the appropriate function at the right time (such as activating the detergent dispenser, spray washing, and draining). Higher-end models may come with a computerized control system. Modern units also include a door latch that must be securely closed for the machine to operate, with some also offering child safety locks.

Water Inlet Valve

This is where water from the household water supply enters the dishwasher. The valve, located inside the unit, opens and closes to allow the correct amount of water during each cycle. When opened, water pressure forces the water into the dishwasher.

Circulation Pump

The circulation pump is powered by an electric motor. During the wash cycle, the pump pushes water into the spray arms. In the drain cycle, it directs the water into the drain hose. The pump assembly is located beneath the basin, at the center of the dishwasher. There are two main types of pumps:

Dishwashers can be set up in either a portable or permanent configuration. Portable models feature finished sides and a top that can double as countertop space. When not in use, the unit sits beside the wall. To use it, simply roll it on casters to the sink, connect it to the faucet, and plug it into a nearby outlet.

For permanent installations, the dishwasher is placed under the existing countertop and secured in place. Hoses beneath the kitchen sink connect directly to the hot water and drain lines, and the unit typically plugs into an outlet under the sink. Both types of installation require a 120-volt grounded electrical line.

Next, let's dive into how to properly use a dishwasher.

How to Operate a Dishwasher

While the dishwasher handles most of the work, human involvement is still essential. Here are some tips to ensure your dishwasher works safely, efficiently, and effectively.

Dishwasher Detergent

Detergent plays a key role in how well your dishwasher works. It helps counteract the effects of hard water by neutralizing mineral deposits. Detergents contain solvents to break down food particles, abrasives to scrub away stubborn residue, and other agents to help food slide off dishes more easily.

You can't just use any detergent in a dishwasher; only those formulated specifically for dishwashers are safe and effective. Non-dishwasher detergents can damage dishes or create excessive suds that may cause the machine to overflow. When choosing between tablets, powder, or gel, it ultimately comes down to personal preference—no one type has been proven to clean better than the others. Just be sure to use detergent that's fresh—within two months of purchase—so it works effectively.

Troubleshooting

One of the most common issues people face with dishwashers is an inability to properly clean dishes. You may notice food remains or detergent residue. The problem could be related to low water pressure, and the water intake valve might need replacement. Another frequent issue is mineral build-up. If your home has hard water, minerals can accumulate and clog the water jets. To clear them, use a wire or pin to clean each jet, and run an empty cycle with vinegar in the detergent dispenser once a month.

Occasionally, dishwashers have difficulty draining properly. The drain hose might be clogged, or there could be a malfunction in the pump. Another possibility is that too many suds are being created, and the dishwasher's sensors are not recognizing the soap foam as water. This can cause the drain cycle to stop prematurely. The solution is to reduce the amount of detergent you use.

Dishwasher Buyer's Guide

All modern dishwashers operate on the same basic principles. Even budget-friendly models are efficient at cleaning. The key to choosing the right one comes down to finding the features that suit your needs and avoiding unnecessary extras. Durability, size, and convenience are the main factors that differentiate models.

Size

Dishwashers come in various sizes to suit different needs. The smallest options are countertop and in-sink dishwashers, which can clean up to six place settings. Countertop models don’t need installation and simply sit on top of your counter. In-sink dishwashers are designed to fit in one side of a double sink and can complete a full load in around 20 minutes. When not in use, a cover on the unit allows it to double as a countertop.

The typical dishwasher width is 24 inches (61 centimeters). However, you can also find 18-inch (46-centimeter) models, often referred to as "apartment-sized" dishwashers. The wider the dishwasher, the more dishes it can hold. For larger families, a 30-inch (76-centimeter) model might be a better fit. Anything larger would likely be a commercial dishwasher.

A unique alternative is the dish drawer, which is about the size of a large kitchen drawer. It uses less water and energy compared to full-sized dishwashers, making it perfect for small kitchens with limited space. Some versions even come in double-drawer models that hold as much as a standard dishwasher. These drawers work independently, offering energy and water savings, and are ideal for kitchens where a traditional dishwasher door could obstruct walkways.

Basins and Racks

In lower-end models, dishwashers feature plastic basins, while mid-range and premium models have stainless steel basins. In cheaper versions, food particles settle in a filter that needs regular cleaning. More expensive models offer self-cleaning filters, and some even include small grinders that break down larger food chunks so they drain with the dirty water.

Dish racks are available in various configurations. The higher the cost, the more flexibility and adjustability the racks offer, with features like collapsible racks, folding tines, extra shelves, and removable racks for easier loading outside the machine. If you often wash large or uniquely shaped dishes, bring them to the store to ensure they'll fit in the racks.

Extra Features

Today's dishwashers are becoming increasingly advanced and energy-efficient, with features that were once considered upgrades now standard on even budget-friendly models. For example, most dishwashers now come with a soil sensor that determines how dirty the dishes are and adjusts the wash time and water usage accordingly to save water. Additional energy-saving features include half-load and quick-wash cycles.

Higher-end models come with WiFi capabilities, allowing you to control your dishwasher from your smartphone. You can start your dishwasher remotely, check the remaining cycle time, lock the control panel (ideal for homes with young children), and get notifications when your rinse aid is running low or if a potential leak is detected. You can even schedule your dishwasher to operate only when local energy usage is low, helping to save on utility bills. Other newer features include a third rack for larger flat items, bottle jets for better cleaning of baby bottles and water bottles, and adjustable racks that move up and down.

Premium dishwashers can be quite stylish, with designs that blend seamlessly into your kitchen cabinetry. Noise reduction is another feature to consider if your kitchen is near a living area. Higher-end models tend to have extra insulation to minimize sound. Keep in mind that dishwashers with built-in grinders for large food particles can be louder than those without.

Energy Use and Cost

One final consideration is water and energy use. The U.S. government's Energy Star program lists the most efficient dishwashers each year to help you choose a model that's best for both the environment and your budget.

What should you expect to pay for a modern dishwasher? In 2021, you could find a reliable, functional model for under $600. If you could spend around $1,000, you'd get features like a third rack, quieter operation, and a more powerful food disposal system. Prices can reach up to $2,000 or more for high-end models that offer features like WiFi connectivity, additional wash cycles, hidden controls, LED lighting, built-in water softeners, and water cleanliness sensors.

Government regulations have significantly boosted the efficiency of modern dishwashers, meaning that unless you have a pre-1990 model, your dishwasher is likely already efficient. ENERGY STAR certified models are 12 percent more energy-efficient and 30 percent more water-efficient than standard models, according to the Environmental Protection Agency. An ENERGY STAR certified dishwasher costs about $35 annually to operate and can save up to 3,870 gallons (17,593 liters) of water over its lifespan.

Using a dishwasher not only saves time but also conserves energy and water compared to washing by hand. How much does it save? An Energy Star-rated dishwasher can save a staggering 7,000 gallons (26,500 liters) of water each year compared to hand washing. It also gives you back 230 extra hours of time and cuts $111 from your utility bills.