WATER YOU DOING?
by
Rosemary Counter
Apr 16
This vs. That: Is Handwashing Better than the Dishwasher?

The very first water-pressure dishwasher, patented in 1885, was invented by American socialite Josephine Cochran after she got tired of cleaning fine china by hand herself.

And who can blame her? Judged purely by the time we save on this chore, a dishwasher beats handwashing any day. 

But there’s another debate happening in homes everywhere—and it’s not just who gets dish duty tonight. Since we’re all looking for ways to conserve water in the kitchen, the question becomes: is it more environmentally friendly to handwash our messy dinnerware or pop it into the machine? 

Photo by Wendelin Jacober on Pexels
Cleaning dishes in an average American home takes anywhere from 6 to 27 gallons of water per load.

This decision matters.

Cleaning dishes in an average American home takes anywhere from 6 to 27 gallons of water per load, according to estimates by the U.S. Geological Survey’s Water Science School. It’s typically a daily task, too, so those gallons add up fast. Since the better method isn’t obvious, we rolled up our sleeves and dove into the research to see which one is best for energy-efficient homes.

The environmental impact of your dishwasher

The difference between 6 and 27 gallons is pretty massive.

It may be tempting to assume handwashing is the more frugal option, while the dishwasher automatically lands on the higher end of this eco-spectrum. But the murky truth is: It depends. 

First, it depends on the dishwasher. If you’ve had the same old appliance since before the fall of the Berlin Wall (circa 1989), it could be gobbling up as much as 16 gallons of water per typical cycle, not including the under-the-tap pre-rinse (more on that later). 

In the mid-1990s, however, the EPA’s Energy Star program, launched to promote energy-efficient appliances and help consumers make better choices, was expanded to cover the dishwasher category. 

Some of the newest Energy Star models use as little as 2.36 gallons of water per cycle.
Photo by cottonbro on Pexels

Today, choosing an Energy Star–certified dishwasher means it’s on average 12 percent more energy-efficient and 30 percent more water-efficient than a non-certified model. Some of the newest Energy Star models with clever eco-wash options use as little as 2.36 gallons of water per cycle. 

Of course, there are more factors to consider than just water.

Unlike your arms, a dishwasher requires electricity—enough to heat the water (which you’d need for handwashing, too) and run the machine. The amount required, as it turns out, is relatively small.

Let’s say your Energy Star appliance uses 4 gallons and 0.87 to 1.59 kWh per load. Using the EPA’s Greenhouse Gas Equivalencies Calculator, that works out to 1.4 to 2.5 pounds of CO2 per load. (For perspective, you probably exhale more carbon dioxide than that each day.)

And, of course, just building that dishwasher has a carbon footprint that needs to be factored in.

One study that looked at real-life dishwashing habits in homes across four countries (Germany, Italy, Sweden and the UK) found that households with a dishwasher used on average 50 percent less water and 28 percent less energy per cleaned item, compared with dishwasher-free households.

The environmental impact of handwashing

That solves that, right? Not so fast.

There’s another factor even the most diligent environmental scientist can’t measure: you. Or, more specifically, your potentially imperfect kitchen habits. 

Do you run the machine half full? (Multiply all those numbers above by two, of course.) Do you run it on super-intense-extra-filthy-mode-plus-heat-dry when a quick cycle would do just fine? Do you leave the tap running while rinsing every plate as you load? (Oops.)

Once you factor in all those extras, you might be wondering, wouldn’t it be better to just do them in the sink the old-fashioned way?

Photo by Jordan Rowland on Unsplash

A new study published in the journal Environmental Research Communications set out for definitive answers.

They calculated that “typical manual washing” would, over the course of 10 years, equal 34,200 gallons of water going down the drain; a dishwasher in the same time would use 16,300 gallons. In terms of greenhouse gases (related to heating water), typical handwashing produced 5,620 kilograms of CO2e over a decade compared to the dishwasher’s 2,090, based on washing four loads a week. (Full disclosure: The study was partially funded by Whirlpool.)

To be fair, the researchers’ definition of typical manual washing involved leaving the tap running the whole time—a convenient method that, admittedly, is probably quite common. They point out that washing by hand “has the potential to have the lowest GHG emissions”—if it’s done right. The trick? Using the two-basin method.

Dishwasher vs. handwashing: the verdict and best ways to save water 

Not all of us have the luxury of passing dish duty over to a machine, and even if we do, there are always those items that need to be treated with extra care and washed by hand.

The difference when it comes to lowering emissions isn’t black and white—the simple goal is to use as little energy and hot water as possible.

Washing by hand, there are plenty of ways to save water: avoid running taps, opt for scraping food residue over pre-rinsing, and follow the two-basin (or two-sink) method.

When washing by hand, there are plenty of ways to save water: avoid running taps, opt for scraping food residue over pre-rinsing, and follow the two-basin (or two-sink) method. Bath one is hot and soapy; dirty dishes stay there for soaking and scrubbing. Bath two is cool for rinsing off, before a towel- or air-dry. Both drains stay plugged the whole time.

That said, while a properly executed two-basin routine is the most climate-friendly pick overall (when judged by lifecycle GHG emissions, since handwashing doesn’t require an appliance to be manufactured), if you already have a dishwasher, particularly an efficient one, the machine might in fact be the more water-saving choice. 

No matter how counterintuitive it feels to press the button and hear the prolonged whir of water in action, the dishwasher has been shown to be more eco-friendly than how most of us use the sink—and potentially significantly more—provided we use it conscientiously. 

When the time comes to replace your clunky, outdated machine, pick the most energy-efficient, modern model you can; run full loads whenever possible, rather than half-loads; and figure out the many energy-saving modes your dishwasher may already have if you’ve never noticed before. 

New washers have advanced technologies like soil sensors to adjust the cycle’s length, filtration systems to use and reuse the same water, and efficient jets that do more with less energy. So you can just give your messy plates a scrape instead of rinsing, and let the dishwasher do the rest of the dirty work.

It truly can be a helping hand in our energy-efficient homes.

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This article offers general information only and is not intended as legal, financial or other professional advice. A professional advisor should be consulted regarding your specific situation. While the information presented is believed to be factual and current, its accuracy is not guaranteed and it should not be regarded as a complete analysis of the subjects discussed. All expressions of opinion reflect the judgment of the author(s) as of the date of publication and are subject to change. No endorsement of any third parties or their advice, opinions, information, products or services is expressly given or implied by Royal Bank of Canada, RBC Ventures Inc., or its affiliates.

Rosemary Counter
Written By
Rosemary Counter

Rosemary Counter is a freelance writer currently curbing plastic cutlery, baby wipes and takeout coffee cups. In her reusable mug, however, she's having as much coffee as she wants.

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