To many of us, the dishwasher is a magical mystery box that transforms dirty dishes into clean ones. But rest assured, there's no wizardry going on: Scientists and engineers are constantly coming up with ways to make these machines work faster and more efficiently.
But dishwashers aren't quite as sexy as 4K TVs or the latest iPad, and announcements about groundbreaking improvements dishwashing don't get tons of headlines.
That's why everything your mom told you about dishwashers is probably wrong. Not that we blame her—we're sure she's a classy lady, but unless she works for Whirlpool, she's probably not up to date on the latest appliance tech. So allow us to set the record straight on some common misconceptions.
Dishwashers use more water than hand-washing.
How many times have you been told to stop being lazy and wash everything by hand to save water? It's easy to understand why some people think dishwashers use water all willy-nilly: It's not like there's a window on the door to let you see how the mystery box works.
But the reality is that the tub doesn't fill up with excess water, and you're certainly not saving resources by doing a load of dishes by hand.
According to the EPA, the water flow rate of most faucets is 2.2 gallons per minute. Most of the dishwashers we've tested, on the other hand, use between 3 and 4 gallons of water in their entire Normal cycle. Unless you're able to wash ten place settings in under two minutes, the dishwasher wins.
Washing by hand gets dishes cleaner.
The logic behind this one is that machines can't see the gunk stuck to your dishes (at least, not yet), so they just spray 'n' pray. Obviously, that makes them less accurate than an eagle-eyed human, right? After all, there's nothing a machine can do that a little elbow grease can't do better.
We've actually already covered this, but it bears repeating: Not only do modern dishwashers do a pretty darn good job getting plates shiny clean, but you have to consider the filth you can't see. There are bacteria living in your sink and on your dishes, and the best dishwashers run hot enough to kill them. Unless you don't mind third-degree burns, you won't be able to do that by hand.
You should prewash everything.
Even if you grew up with a dishwasher, you still couldn't catch a break: Mom made you wash all the dishes before you washed the dishes. Although less of a chore than doing the whole routine by hand, prewashing wastes time and water. Maybe it was just an excuse to get you to develop good work habits, but prewashing nowadays is largely unnecessary.
Current dishwasher detergents use enzymes that react with food particles, literally eating them away. We neither scrape the plates beforehand nor prewash them in our lab tests, and most dishwashers easily remove meat, egg, and milk stains that we've baked on and left there for 24 hours. This is despite the fact that we use far heavier stains than most people would leave on their plates after a meal.
Laziness: 1. Mom: 0.
You can just toss knives in the dishwasher.
The variety of things you can wash in the dishwasher is pretty surprising, but perhaps even more surprising is the number of mundane kitchen items you shouldn't put in there. Although measuring cups and even certain cutting boards are fine, your kitchen knives should always be washed by hand.
There are numerous ways a dishwasher can ruin your knives. It exposes knives to high heat, detergent, and contact with other utensils, which can all dull the blade. To keep the edge keen, make sure you're washing it by hand, then immediately drying with a towel.
You shouldn't wash plastics.
This one is only half-true. We're sure you've heard that the high temperatures of a dishwasher can melt or warp plastic. But in point of fact, there are plenty of plastic containers that will emerge unscathed from a modern machine.
Some dishwashers have a Light or Delicate cycle designed to handle stemware and plastic; these use less water and lower temperatures than the Normal or Heavy cycles. But you should still make sure your tupperware is labeled "dishwasher-safe," and read your appliance's instruction manual to see how hot it gets.
And make sure you're loading them on the top rack, as far away from the machine's heating element as possible.
Hero image: Flickr user "n1ct4yl0r" (CC BY-NC-ND 2.0)