How Dishwashers Work

Here are the main parts of a dishwasher:

Control Mechanism

The control mechanism is located inside the door behind the control panel. Many units use a simple electro-mechanical system: a timer determines how long each part of the cycle lasts and activates the proper function at the proper time (such as the detergent dispenser, wash spray and draining functions). Units that are more expensive might have a computerized control system. Modern units also have a door latch that must be closed for the unit to run. Some also have child safety locks.

Water Intake Valve

This is where water from the home's water supply enters the dishwasher. Mounted on the inside of the dishwasher, the valve opens and closes to let in the proper amount of water during a cycle. When the valve opens, water pressure drives the water into the unit.

Circulation Pump

An electric motor powers the circulation pump. During the washing cycle, the pump forces water up into the spray arms. During the drain cycle, the pump directs the water into the drain hose. The pump assembly is mounted beneath the basin, in the center of the dishwasher. There are two main types of pumps:

Dishwashers can be installed in either a portable or permanent configuration. Portable units have finished sides and a top that can be used as a countertop. When not in use, the machine sits in place next to the wall. When it's time to run a cycle, the unit can be rolled on casters over to the sink, where it connects to the faucet and plugs into a nearby outlet.

In a permanent installation, the dishwasher goes underneath the existing countertop and bolts into place. Hoses underneath the kitchen sink connect directly to the hot water line and the drain line, and the unit usually plugs in under the sink as well. Both types of installation require a 120-volt grounded line.

Next, we'll look at how to use a dishwasher.

Even though the dishwasher does most of the work, humans play a part, too. Here are some guidelines that can help your dishwasher operate safely, effectively and efficiently.

Detergent

Detergent is an important consideration when running a dishwasher. Detergents counteract mineral deposits, or hardness, in the water. They contain solvents that help dissolve food, have abrasives that scour away stuck-on gunk and help food slide off dishes more easily.

You can't use just any detergent in a dishwasher; only detergents specially formulated for dishwashing machines will work. Other detergents could damage dishes or generate so many suds that the dishwasher would overflow. Which detergent to choose — tablet, powder or gel — is really based on personal preference. One type hasn't been shown to clean better than another type. Just make sure the detergent is fresh — less than two months old — or it won't clean as well.

Troubleshooting

The problem most people encounter with dishwashers is a simple inability to get the dishes clean. There might be stuck-on food or residue from the detergent. A water pressure problem may be the culprit. You may need to replace the water intake valve. Another common problem is mineral build-up. If your house has hard water, the mineral build-up can clog the water jets. Clear each jet with a wire or pin and run an empty load with some vinegar in the detergent dispenser once a month.

Sometimes, a dishwasher has problems draining properly. There could be a clog in the drain hose or a problem with the pump. It's also possible that the dishwater is getting too sudsy, and sensors in the washer aren't detecting the soap foam as water. This causes it to shut down the drain cycle too early. Just use less detergent.

Modern dishwashers all function in the same basic way. Even cheaper models do a good job of cleaning dishes. That makes buying one a matter of finding features you'll use and avoiding ones you don't need. Durability, size and convenience are the primary factors that set one model apart from another.

Size

Dishwashers come in a wide variety of sizes. The smallest are countertop and in-sink dishwashers, which can wash up to six place-settings. Countertop units don't require installation, as they sit on top of your counter. In-sink dishwashers typically fit into one-half of a double kitchen sink and can wash a complete load in about 20 minutes. When not in use, a cover on the unit lets it serve as a countertop.

The standard size for a dishwasher is 24 inches (61 centimeters) wide. However, 18-inch (46-centimeter) units are available, sometimes known as "apartment-sized" dishwashers. Obviously, the wider the dishwasher, the more dishes it can hold. If you have a large family, a 30-inch (76-meter) model might be the right size. Any larger than that, and you're probably looking at a commercial dishwasher.

A more unique offering is the dish drawer, a small dishwasher the size of a large kitchen drawer. It uses less water and energy than a full-sized dishwasher uses and is suited for small kitchens that don't have enough room for a full-size unit. However, they also come in double-drawer models that can hold as many dishes as a standard dishwasher. These drawers function independently and, in addition to their water and energy economy, are perfect in kitchens where a dishwasher door would block a walkway.

Basins and Racks

Lower-end dishwasher models have plastic basins, while some mid- and all high-priced units have stainless steel basins. In cheaper models, bits of food settle into a filter that must be manually cleaned on a regular basis. Models that are more expensive have self-cleaning filters, and some include small grinders that grind up large chunks so they drain with the dirty water.

Dish racks come in many configurations. The more you pay for the dishwasher, the more flexibility and adjustability you'll get, with collapsible racks, folding tines, extra shelves, and removable racks for loading outside the machine. If you have large or oddly shaped dishes that you'll be washing regularly, take them to the appliance store to make sure they'll fit the racks.

Extra Features

Today's appliances are growing ever smarter and more energy efficient, with past upgrades now standard on even the least-expensive models. One example: Most dishwashers now feature a soil sensor that saves water by sensing how dirty your dishes are and adjusting the wash time and water amount accordingly. Other energy-saving options include half-load and speed-wash cycles.

More expensive models boast WiFi connectivity, allowing you to control your appliance from your smartphone. You can not only start your dishwasher remotely, but also check the remaining cycle time, lock the buttons (should younger kids be at home), and receive alerts when your rinse aid is low or there's a possible leak. You can even program your dishwasher to run only when local energy consumption is low, which may save you money. Other newer features include a slim, third rack for large, flat items; bottle jets to better clean baby bottles and water bottles; and racks you can move both up and down.

Expensive dishwashers can be stylish, with fronts designed to look like kitchen cabinets. Noise suppression might be worth the extra cost if your kitchen is close to your living room. Dishwashers that are more expensive have heavy insulation against noise. Note that dishwashers with grinders for large food chunks are louder than those without them.

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 select a model that's best for the environment and your pocketbook.

So how much can you expect to pay for a modern dishwasher? In 2021, you could snag a reliable, functional model for less than $600. If you could afford to shell out $1,000, that would get you features like a third rack, a quieter machine and a powerful food disposal. Prices go all the way to $2,000 and more for dishwashers with every possible feature, including WiFi connectivity, additional cycles, hidden controls, LED lights, built-in water softeners and water cleanliness sensors.

Government regulations have greatly improved the efficiency of modern dishwashers, so unless your dishwasher is a pre-1990 model, it's probably efficient. ENERGY STAR certified dishwashers are 12 percent more energy-efficient and 30 percent more water-efficient than standard models, according to the Environmental Protection Agency. A standard-size ENERGY STAR certified dishwasher costs about $35 annually to run and will save about 3,870 gallons (17,593 liters) of water over its lifetime.

Using a dishwasher saves time, but it even saves energy and water compared to washing dishes by hand. How much? An Energy Star dishwasher saves an amazing 7,000 gallons (26,500 liters) of water annually, compared to washing dishes by hand. It also gifts you with an extra 230 hours of time and shaves $111 off your utility bills.