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Dishwasher vs hand washing: which is greener?

By Celia Topping Wednesday 05 May 2021

washing dishes

There aren’t many of us that enjoy washing dirty dishes by hand. That’s why dishwashers were invented! But in recent years, concern over the eco-friendliness of dishwashers has found the more green-minded of us reverting to hand washing – for the sake of the environment. 

But what if your hand-washing habits aren’t quite as eco as you think? And what if dishwashers really are more energy-efficient? Believe it or not, considerable research has gone into the question of dishwasher vs hand washing! Read on to find out if you can start using your dishwasher again with green peace of mind. 

How much energy does a dishwasher use?

This all comes down to how modern and energy-efficient your machine is. The Energy Saving Trust worked out that the average running cost of a dishwasher is between £37 and £48 a year. And the most energy-efficient, A-rated models cost around £7 a year less to run than the lowest-rated machines. Slimline dishwashers cost slightly less – at £23 to £37 a year. 

How much water does a dishwasher use? 

This depends on the machine, and also how you use it. If you have a super-energy-efficient machine, it will use less water than an old one. And if you cut out the pre-rinse stage in the cycle, you’ll save even more water. 

According to the Energy Saving Trust, hand washing dishes makes up 4% of the average household’s water use – whereas using a dishwasher uses 3% less, accounting for just 1% of our water bills. Older appliances, manufactured before 2000 used around 25 litres of water per cycle, while a more modern one would use 10 litres per cycle on an eco setting. It’s a big difference, caused by the newer machines reusing the water, rather than constantly piping in fresh water. 

And what about when we compare it to hand washing? A running tap flows at around 2 gallons (9 litres) per minute. So if you wash everything under a running tap, it’s estimated you could use up to 9 times as much water as a dishwasher uses. Better hand washing habits can significantly reduce this amount, so we’ll come to that in a moment. 

Interested to know more about the impact of water consumption on the environment? We did the hard work for you and put everything together in our guide on the impact of water use on the planet, and how saving water can reduce our carbon footprint. 

Do dishwashers use hot water?

Dishwasher water has to be hot, so dishes are cleaned properly. But in terms of energy-use, the question is whether the water is hot when it goes in, or if the water is made hot by the machine. If you buy a modern dishwasher, it won’t use any of your home’s hot water supply. It’ll take in cold water, then heat it internally to around 54 - 62°C.  

Because they don't use your home’s hot water, modern dishwashers are far more efficient. For this reason, dishwashers are also better at getting plates really clean and sanitised – because who could actually bear to put their hands into water that hot?

How much electricity does a dishwasher use? 

Generally speaking, a dishwasher isn’t a very energy-intensive appliance. Nothing like a carbon-guzzling tumble dryer for instance. Modern machines have a power rating of around 1,050 to 1,500 watts. You can see the exact kWh on the appliance’s energy rating. And if you don’t use the heated drying stage at the end of the cycle (and frankly, it’s not really necessary), you can reduce the machine’s carbon emissions by 11%1.

Read more about what energy ratings mean, and how to get the best out of them, in our useful guide. 

Dishwasher vs hand-washing, which is cheaper? 

First, you’ve got to factor in the initial cost of the dishwasher, which can range from around £170 to well over £1,000. And going cheap doesn’t make financial sense in the long run – cheaper models are likely to be less energy-efficient, and need replacing sooner. When it comes to water and energy use, it depends on your habits. Generally, if you only use your dishwasher once it’s fully loaded, it should save you money. 

For more tips and recommendations on how to save energy and money on your electricity bills in the kitchen, check out our guide. 

The carbon footprint: dishwasher vs hand-washing, which is greener? 

Because a dishwasher uses less water and less energy to heat the water, this means the carbon footprint of a dishwasher is actually smaller than if you wash by hand. Recent studies state 5,620 kgs of greenhouse gases (GHGs) are produced over a 10 year period from hand-washing 32 sets of dishes per week. This comes from the energy used to heat up the water. A dishwasher on the other hand, emits 2,090 kgs of GHGs over the same period. The figures speak for themselves. Hand-washing creates over double the amount of GHGs as dishwashers, and creates about the same carbon emissions as 3 flights from London to Tokyo! 

The verdict: are dishwashers worth it?

You’ll be happy to know you can take off those Marigolds and safely return to your dishwasher! Everything considered, dishwashers are better for the environment than washing by hand. As long as you’re prepared for the initial expense, and you’re using a modern, energy-efficient dishwasher in the most efficient way possible.

This means not pre-rinsing, and running your machine only when it’s full, and using the eco setting. If you don’t fill your dishwasher every time, or use an old, less efficient model, you could be better off hand-washing. 

If you’re wondering how old and efficient (or inefficient) your dishwasher is, take a look at the manual, if you still have it. If not, it’s easy enough to check online – just look up the make and model of your machine. 

How to hand-wash more efficiently

You know that running the hot tap while you scrub madly, randomly squirting detergent, probably isn’t the most eco-friendly method. It may seem quicker – but from an eco point of view, it’s a total no-no. Here are a few tips to green-up your hand-washing:

  • A split sink is the key to efficient hand-washing2. Fill up one sink with hot water and (an eco-friendly) washing up liquid, and the other just with hot water.

  • The water should be as hot as you can bear, to get the dishes as clean as possible.

  • Pre-soak your dishes in the sink of hot soapy water to loosen any stubborn dried-on bits. This saves your energy, as well as water, when it comes to scrubbing them clean! 

  • Once the sink is full, there’s no need for a running tap which is wasteful. Just keep the dishes in the water to soak.

  • After they’ve soaked for a few minutes, get scrubbing! 

  • Use the other sink of clean hot water for rinsing off the soap. Again, no need to rinse under a running tap. 

  • Either dry the dishes with a tea towel for a smear-free finish, or let them air dry.

By following these tips,  you’ll only use the same amount of water as an energy-efficient dishwasher. (And if you teach your kids to do it, your energy is saved completely!) 

5 simple tips to use your dishwasher more efficiently  

Every dishwasher, regardless of age or rating, can be made more efficient by following these few easy tips:

  1. Don’t pre-wash your dishes – apart from a quick scrape,  you don’t need to rinse your plates. Modern dishwashers are pretty thorough!

  2. Always fill your dishwasher – if you press start with a half-empty load, you’re wasting half the machine’s energy and water. Fill it up before you wash!

  3. Load it properly – it might sound fussy, but a poorly loaded dishwasher means some dishes don’t get cleaned, so they'll have to go through again. Glasses, cups and plastic up top, roasting dishes down below and large items at the back and sides. Face everything towards the centre of the machine, and don’t overload by squeezing in too many items. 

  4. Use the eco setting – most modern dishwashers have this setting. It works by heating the water slowly over a longer cycle, which uses around 20% less energy.

  5. Check out “time of use” home energy plans – tariffs like Economy 7 charge less per unit of electricity at night than in the daytime. This encourages customers to use their appliances during the night, when demand on the grid is lower. You could use the delayed-start function to benefit from these savings. 

Remember to read our fab new article on how food waste impacts the environment – and make sure you’re not scraping away food that could be re-used or composted.

How to choose an energy-efficient dishwasher

Using an inefficient dishwasher is not only bad for the environment, but your bank balance as well. Choose the wrong one and you could be losing up to £290 over the life-cycle (around 8 years) of your dishwasher, according to Which?3 

There are so many makes and models of dishwasher on the market today, it can be a bit mind-boggling. Here are a few tips to bear in mind:

  • Since March 2021, energy labels have changed slightly. All those +++ symbols have been replaced by a much simpler A to G scale. The new generation labelling means an energy-efficient dishwasher with an A+++ rating could move to class B, C, or even lower – but without actually being any less efficient. The Class A rating will initially be empty, to leave room for more energy-efficient models of the future. 

  • Top rating dishwashers use less electricity and water, so these are the best ones. 

  • A dishwasher’s energy rating label relates to the eco setting. So if you use your dishwasher on the ordinary setting, it won’t be as energy-efficient as the energy label says. 

  • Modern, energy-efficient dishwashers fill up with cold water from your home supply, and heat it inside the machine. Older models relied on hot water from your supply, which used more energy. 

  • It’s important to think about size when choosing an energy-efficient dishwasher. DIshwashers always fill to capacity, so if you live in a small household, choose a slim or compact dishwasher for best efficiency. 

Beyond using an energy-efficient dishwasher, how can I save energy at home? 

At OVO, we’re all about green energy, energy-efficiency, protecting the planet and saving you money. So here are just some of the useful articles we’ve created to help you do just that:

We’ve also created the OVO Greenlight tool, to help you understand your carbon emissions, and learn how to start reducing them. From home energy to transport emissions, we reveal your carbon impact, and give you suggestions for how to lighten your carbon footprint. The tool is available to all OVO members, on any of our green home energy plans

Join OVO today and find out how you can become a carbon-crunching community member! We don’t only offer 100% renewable electricity as standard4, but also:

  • A tree planted in your name every single year you’re with us5

  • 3-5% Interest Rewards for every year your account has a positive balance6

  • An award-winning smart meter experience (Uswitch 2020)

  • A £50 gift card every time you introduce a friend to us

 

Get a quote 

 

Sources and references:

1.  https://grist.org/climate/science-dishes-out-an-answer-on-the-old-handwashing-vs-dishwasher-debate/

2.   If you don’t have one, you could use your sink for the hot soapy water and put a washing bowl on the counter for the soapless hot water.

3. https://www.which.co.uk/reviews/dishwashers/article/dishwasher-energy-running-costs-aabVK5u95flB?source_code=911CRJ&gclsrc=aw.ds&&gclid=Cj0KCQjw1a6EBhC0ARIsAOiTkrFo-oZf4NFLoPdJZr0ZIB4EyrTspBXZFqENvrUznQb4qZHdxM2vWrYaAjnYEALw_wcB

4.  100% of the renewable electricity we sell is backed by renewable certificates (Renewable Energy Guarantee of Origin certificates (REGOs)). See here for details on Renewable Energy Guarantee of Origin certificates and how these work. A proportion of the electricity we sell is also purchased directly from renewable generators in the UK.

5.  Each year, OVO plants 1 tree for every member in partnership with the Woodland Trust. Trees absorb carbon dioxide from the atmosphere, so tree-planting helps to slow down climate change.

6. Interest Rewards are paid on credit balances of customers paying by monthly Direct Debit. It is calculated at 3% in your first year, 4% in your second year and 5% in your third year (and every year thereafter) if you pay by Direct Debit. Interest Rewards are paid monthly based on the number of days you have a positive balance and the amount left in your account after you’ve paid your bill. Full terms apply