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We've written at length about how using a dishwasher is more efficient than washing dishes by hand. Still, instinct is difficult to overcome. Dishwashers are machines, after all, and to many they just seem more wasteful than the old-school alternative.
On top of that, arguments persist about the costly dishwasher manufacturing process, and how it factors into their overall sustainability. But as it turns out, even when you take mass production into account, dishwashers are the most efficient means of cleaning your dishes.
This isn't sponsored content—it's just science.
Mother Nature Network recently compiled data for a "life cycle analysis" of dishwashers, including the energy required to build the machine and the water and electricity use over its 10-year lifespan. The magazine then compared it to the environmental cost of hand-washing dishes.
Here's a brief rundown of the math:
Using data from Low-Tech Magazine, MNN estimates it takes 340 kWh of energy to make a typical dishwasher. Meanwhile, an Energy Star-rated machine averages 295 kWh per year to run (1.37 kWh per use, which is on the generous side). In other words, it only takes a little more than a year for your dishwasher to consume more energy than it took to make it.
Now let's look at hand-washing. According to a 2011 study by the University of Bonn, the average American goes through a whopping 40 gallons of water and and 3.5 kWh of electricity per hand-washing session.
Compare that to the four or five gallons of water and 0.5-1.3 kWh used by most dishwashers, and you begin to see how wasteful hand-washing really is—both for the environment and your utility bill. In fact, MNN arrives at the conclusion that it only takes Americans 10 hand-washing sessions to consume more energy than what's needed to manufacture a dishwasher.
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