There's an old saying if you put three people in a kitchen after dinner, they'll all have a RIGHT way to load the dishwasher — and all those ways will be different. Can you wash wine glasses and knives in the dishwasher? Is rinse agent a scam or really necessary? Which is best: powder or liquid? And the biggie — do you have to RINSE the dishes before you wash? To settle these disputes unequivocally, I asked the dishwasher engineers at Kenmore and my local Sears repairman for their advice.
Dishwashers Have Changed
We are used to our TV technology evolving fast, but few of us are aware of the technological changes that have taken place in dishwashers over the last 10 years. Energy Star standards have pushed engineers to make dishwashers that wash faster and hotter, while using less water and energy. High efficiency wash systems use 41% less water and 37% less energy than products built in 2001. And it's not just water and energy use that have changed; how dishwashers handle food and scrub our dishes is different too.
Do You Need to Rinse Dishes First?
In most cases you DON'T need to rinse the dishes. Dishwashers made in the last 10 years have built-in methods to handle food scraps. First, the temperature of the water is higher than ever to soften food. Sprayer power has increased dramatically. Rack design and sprayer head placement now give the water better access to the dishes. As long as you don't overload or stack dishes, the engineers I spoke with said you don't need to rinse first. Scraping food off should be enough.
So Where Does the Food Go?
Most dishwashers use grinders, integrated disposals, to pulverize food and wash it down the drain. But those motors create a lot of noise and use a lot of energy, so many dishwasher manufacturers are phasing them out. New systems, especially those with lower noise levels (under 44 dB) use a funnel-like system of filters. Hot water temperatures help break the food waste down so it can be washed away, but manufacturers advise emptying filters regularly for any food that remains.
Dishwasher Quick Rinse Uses ½ Gallon of Water
If you are still paranoid about not rinsing, you can always run the quick rinse cycle. It's way more efficient than rinsing by hand. Most home faucets run at about 2 gallons a minute. Rinsing dishes from my family dinner took me about 3 minutes of running water — that's 6 gallons to rinse by hand compared to ½ gallon to run the quick rinse.
How Much Water Do Modern Dishwashers Use?
My dishwasher uses about 4-4.5 gallons of water per cleaning cycle. The number varies because most dishwashers today have soil sensors that evaluate water clarity to see how many food particles the water contains. If the water is still dirty, the wash cycle continues. When the water runs clear, the soil sensor knows the dishes are clean and ends the wash.
Compared to Hand-washing?
Most people know that hand-washing the dishes uses more water than the dishwasher, but I had no idea how dramatic the difference was. Timing my water consumption to wash the breakfast dishes, I used over 13 gallons. If I had washed that same load in the dishwasher it would have used 4- 4.5 gallons. Even if you only have half a load, it's still more water efficient to use the dishwasher. In fact, the US Department of Energy published findings that washing the dishes by hand will take 230 more hours each year than washing in the machine. It will use over 5000 more gallons of water, and because the dishwasher gets temperatures to 140 degrees, using the machine is more sanitary. One key to efficiency: choose "smart wash" or "economy cycle" instead of "normal" or "pots and pans." This mode can cut up to an hour from the cleaning time, employing soil analyzers to get you the cleanest dishes with the least amount of water and energy.
What Detergent is Best? Do You Need Rinse Agent?
According to the Kenmore engineers I spoke with, the best dishwasher detergent choice is tabs or all-in-one packs. They premeasure the exact amount of detergent and add a rinse agent for you so you don't need to remember to fill the reservoir. If you don't use a pre-pack, the engineers say there's no difference between liquid or powder, but that using rinse agent is a MUST. The Energy Star specs that have guided modern dishwasher technology mandate less water and energy consumption. A key tool in meeting those specs is rinse agent, which sheets food debris off dishes easier and allows the dishwasher to have a shorter drying cycle without leaving spots on glasses.
What Can and Can't Go in the Dishwasher
Knives: Our service man Neil Lowery from Sears says most high-end knives are made of carbon-steel and CAN go in the dishwasher, but less expensive knives have more iron and thus are more susceptible to rust. Manufacturers of knives say that technically the knives can go in (except those with wooden handles) but that the biggest issue is when the knives are placed too close to other objects that will bang into them and dull or ding the blades.
Wine Glasses: As long as the stems are clear of any other dishes, Neil says they are fine for the dishwasher's top rack. And many newer dishwashers allow you to lower the top rack to make room for long-stemmed glasses. Manufacturers of very high-end wine glasses like Riedel say their super thin glass is hand-wash only. But the Waterford Crystal site says their glasses can go in on Crystal mode which keeps temperatures under 149 degrees. Best practice is to check with the manufacturer.
Plastic/Melamine plates: Totally safe in the dishwasher. Older plastic plates may fade due to high dishwasher temperatures, but newer Melamine plates are much more fade-resistant.
Pots and Pans: I am constantly amazed at what a good job my dishwasher does on pots and pans with baked-on food. Some dishwashers have rotating spray heads that sit on the back wall to help clean baked-on stuff from casseroles and baking dishes. On mine, it's called a Turbo Zone, but if yours has this feature you turn the food side of the pan toward the back wall, which would normally be a loading no-no. Other dishwashers have a "pots and pans" setting for when you've really loaded in the big dishes.
Loading the Dishwasher
Some people insist utensils have to go in with the head up. Others insist on using the hanging racks that go over many utensil baskets. But the engineers and our service man agree, utensils head in, tines down on forks, points down on knives is safer and cleans just as well. The perforations on modern baskets are designed to allow maximum water spray and food drainage.
The Golden Rule of Dishwasher Loading: If the dirty part of the dish doesn't have a clear path to the sprayer arm, it has a good chance of staying dirty. Our engineers say that overloading is the worst thing you can do for dishwasher performance. That may mean washing a little more frequently, but given the reduced water consumption (compared to older dishwashers and washing by hand) and the fact that free range dishwasher loading means no rinsing, the tradeoff seems worthwhile.
Finally, A Little Bonus: What Do You Get In A High-End Dishwasher?
I asked the engineers what you get in a high-end dishwasher that you don't get in a low to middle ranged model. Basically, high-end dishwashers have more cycle choices, scrubber jets, a stainless steel tub interior, and more cosmetic upgrades like a more industrial design. But the biggest technological difference is the sound level. High-end dishwashers can be as quiet as 40 decibels. Cheaper dishwashers run as loud as 47 Decibels. Seven to ten years ago, dishwashers were much louder: 55-65 decibels. That doesn't seem like a big difference but the Kenmore engineers explain that in that range, a 3 decibel decrease is equivalent to cutting the sound in half. A blender is 88 decibels. Standing 50 feet away from a freeway, the noise is 70 decibels. An old dishwasher was 65 decibels and a new dishwasher can be as quiet as 40 decibels.