Dishwasher vs hand washing: which is the most efficient method?
Which? tests show even the least water-efficient dishwasher still only uses half the amount of water compared to washing by hand
Our in-depth testing has found that dishwashers are, on average, four times more water efficient than washing by hand per place setting.
The most water-efficient full-sized dishwasher uses almost 10 times less water to wash the same amount of dishes as hand washing them.
Find out how much water it takes to wash up a meal for two, what our testing shows and how the energy use compares between using a dishwasher and washing in your kitchen sink.
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Dishwashers vs hand washing
Plate for plate and glass for glass, full-sized dishwashers are more efficient than their slimline counterparts. This is because you can wash more dishes in them with only a little bit more water used.
However, even if you were to use the most thirsty slimline model available, it would still use half the water that hand washing does.
| Method of washing | Best (litres) | Average (litres) | Worst (litres) |
|---|---|---|---|
Full-sized dishwasher | 1 | 2.2 | 4.2 |
| Slimline dishwasher | 1.8 | 2.7 | 4 |
| Handwashing | n/a | 9 | n/a |
Still, the debate rages on over whether it's better to wash your dishes by hand or in the dishwasher – and whether or not you should rinse the soap suds off after washing up by hand – as you can see from the comments when we posted the above video on Instagram
Read our dishwasher reviews to find out which match fantastic energy and water-efficiency with brilliant cleaning and drying. Which? members can also discover our best dishwasher tablets and best washing-up liquids too.
What our dishwasher testing shows
When washing up, we estimate that you can wash around two place settings* with one washing-up bowl (average capacity of nine litres) before you would need to empty the water and fill it again.
However, dishwashers don't just wash one or two place settings at a time; some can wash up to 16 in one wash. To make it an even comparison, we filled a dishwasher up to the maximum before putting it on.
We then divided the water used in one wash by enough to just wash two place settings - one washing-up bowl. Doing this, we can get an even comparison.
We found that all dishwashers, even the least water-efficient, can wash twice as many dishes using the same water.
- 19 sets - best dishwasher
- 9 sets - average full-sized
- 7 sets - average slimline
- 4 sets - worst dishwasher
- 2 sets - hand washing
This is based on all the dishwashers we've tested in the past 10 years.
What about energy use?
Dishwashers on average use about 1.12kWh of energy per wash. This costs roughly 27.44p, based on 24.5p per kWh, although that will of course depend on your energy provider.
How much energy used to heat up water for your washing up bowl will depend on the heater.
We calculate energy running costs for dishwashers. The most efficient costs over half as much to run, compared to the priciest.
If you have a gas-heated water tank, it isn't an easy comparison (a bit like apples and pears).
Gas is typically cheaper than electricity, but is worse for the environment.
If using an electric immersion heater that's 3kW, it will cost roughly 12p to heat up a nine-litre washing up bowl**.
As dishwashers are able to wash more in a single wash, using less water (and hence having less to heat up), they could be more energy-efficient too.
*The Association of Home Appliance Manufacturers (AHAM) defines the following as one place setting: a cup, saucer, dinner plate, side plate, fruit bowl, glass, dinner fork, salad fork, knife and two teaspoons.
**Based on a unit of electricity cost of 24.5p per kWh (April 2024 price guarantee).
Want to know more? Read our guide to dishwasher energy running costs to find the most efficient dishwasher for your home
It always helps to buy the best dishwasher you can afford. Which? members can browse all our Best Buy dishwashers, which start from £400.
We've also tested and recommended Great Value dishwashers starting from just under £300 and Eco Buy dishwashers starting from just over £400.
Members can even filter our dishwasher reviews by annual running costs, as well as by brand, retailer, price range, test results and more. We also test compact dishwashers and slimline dishwashers.
Not a Which? member yet? You can still access plenty of dishwasher advice for free. Why not browse our Which? subscription options, or even gift an annual subscription?
