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.
Dishwashers come in a wide variety of sizes. The smallest are in-sink dishwashers. These units fit into one-half of a double kitchen sink, use less water, 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 wide. However, 18-inch 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 model might be the right size. Any larger than that, and you're probably looking at a commercial dishwasher.
The Dish Drawer is a small dishwasher the size of a large kitchen drawer. It also uses less water and energy than a full-size dishwasher uses, and is suited for small kitchens that don't have enough room for a full-size unit. They also come in double drawer models that function independently.
Basins and Racks
Lower-end 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, bring them along to the appliance store to make sure they'll fit the racks.
Controls and cycle types are among the extra features that can drive up the cost of a dishwasher. Cheaper units have mechanical controls, using a dial and a timer to regulate the different cycles. Push-button controls with digital readouts and computerized timers are more expensive, but they don't clean dishes any better. Some dishwashers offer a cornucopia of cycle options, including high pressure super heavy-duty, crystal/china and sanitizing modes. However, three basic cycles will cover most of your dishwashing needs: Light, Normal and Pots & Pans. A Rinse and Hold cycle lets you clear extra food off dishes that will be sitting in the washer for a few days before they are cleaned. Hot Dry cycles dry dishes more quickly, but use extra energy.
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 guidelines have a chart that lets you compare annual energy usage of many different dishwasher models. If you're keeping an eye on your utility bills and are concerned about the environment, this chart can help you find the right model. How much can you expect to pay for a modern dishwasher? A reliable, functional model without any extra features costs around $200. The $300 to $700 price range contains models with extra cycles, adjustable racks, larger tubs and better materials. Prices go all the way to about $2,000 for European dishwashers with every possible feature, including 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. Using a dishwasher saves energy and water, and it certainly saves time. This depends on individual dish washing habits, as some people take more time and water than others. The Association of Home Appliance Manufacturers estimates that a dishwasher saves about six hours per week, and uses just over eight gallons of water for one load of dishes. It takes roughly 16 gallons to wash them by hand [ref].
For lots more information on dishwashers, check out the links on the next page.