Is your dishwasher saving the planet?

As one of Melbourne’s many renters, I’ve inspected some very ordinary apartments. Places with no light, or noisy neighbours, a poky kitchen, strange smells, mysterious stains. Can I see myself living in this flat?, I ask.

If often comes down to the dishwasher. Give me that emblem of modern convenience, and you can put me in a dark shoebox, next to a rubbish dump, where the neighbours pump out country music every night. (Actually, no country music; I wouldn’t go that far.)

Dishwasher
I never thought I’d be taking a photo of my dishwasher for homework. But here we are. (Source: author’s own)

Dishwashers are ever so convenient, save us hours of work, and do a much better job than mere hand washing.

You may have heard, too, that they’re are better for the environment. Is this true?

There aren’t all that many studies in this area, unfortunately. For some reason, scientists think there are more important things out there than measuring how people wash up after a meal.

But we’ve got enough information to make a call, so let’s break it down.

Water

A 2007 study by the University of Bonn, Germany, found that dishwashers used at least 80% less water than washing by hand. This study was funded by dishwasher manufacturers (Big Dishwasher, if you will), so perhaps we can’t really trust its findings.

So let’s look at an independent study from the USA. It was even more keen on the water savings from dishwashers, saying that a large load would take 170.5 litres of water to wash by hand, compared to less than 20 litres in a dishwasher.

Australians use less water than Americans when washing our dishes, probably because we live in such a dry continent. But the difference is not nearly enough to change the water question. We’ll award this category to dishwashers.

Dishwashers 1: Hand-washing 0

Not every kitchen has room for a dishwasher, unfortunately. (Source: Kim Siever, flickr)

Energy use

The same American study shows that dishwashers use slightly more energy to clean your dishes than you do when you’re washing them by hand. The study was from back in 2013, and appliances are getting more efficient by the year, so it might be closer to even now.

But you also have to include the energy that goes into making the dishwasher. An MIT study estimated that 88 to 95% of a large appliance’s energy impact came while it is being used, with only a small percentage coming from its production.

So it’s not a big difference, but enough to give hand-washing its first win.

Dishwashers 1: Hand-washing 1

Greenhouse gases

Down to a tie-breaker: the impact on climate change from hand-washing your dishes compared to putting them in a dishwasher.

You might think that since the dishwasher uses more energy, it would lose this category by default. But you’d be wrong. Remember the extra water that hand-washing uses? Well, that needs to be transported to your kitchen, and then transported back to a treatment plant.

This means that over the course of a year, an American family that hand-washes its dishes produces 113kg more CO2 than it would if used a dishwasher. That’s about the same as burning a tank of petrol.

Final score: Dishwashers 2 defeats Hand-washing 1

Don’t despair if you don’t have a dishwasher, though – you can still save water and energy by filling your sink rather than using running water. And if you have a dishwasher, don’t pre-rinse your dishes, because that negates the environmental benefits of your appliance.

Happy washing up!


7 Responses to “Is your dishwasher saving the planet?”

  1. Sam Heselev says:

    You’re exactly right Sarah, rinsing the dishes removes any environmental benefits of using the dishwasher. Apparently, dishwasher manufacturers recommend that you ‘scrape’ scraps off first, but of course, that doesn’t always do the job.

  2. Sarah Nielsen says:

    I personally don’t own a dishwater (yet!) but I have listened to my mum and aunt go back and forth on this topic many times! My auntie uses a dishwasher and is forever complaining that it doesn’t completely clean the dishes properly and she needs to rinse them off under the sink first. I wonder if other people have this issue, and if it’s common, would this cancel out the water saving and greenhouse gas perks? Great article!

  3. Siyuan Chu says:

    Really interesting! I will share this blog with my roommate to persuade her as she thought hand wash might be more environmental friendly.

  4. Sam Heselev says:

    Haha, glad your environmentalist credentials remained intact!

  5. Melissa Yoon says:

    Ah, I actually had this debate in real life with my cousin a little while ago! He came to stay with me and criticised me for being a “bad environmentalist” by “wasting water and electricity” from using the dishwasher instead of hand washing. We both looked it up and turns out I wasn’t being a bad greenie after all 🙂

  6. Sam Heselev says:

    Thanks Xuexiao! Yeah, it seems counter-intuitive, but modern dishwashers are really efficient and will save heaps of water. If you’ve got one, make use of it!

  7. Xuexiao Yang says:

    Interesting topic and thanks for the ideas! Previously I just thought that the dishwasher was not good as it usually takes hours to wash the dishes. After reading your words, comparing the water usage and the other characters, I think I should change the way of dishwashing from now on.