Dishwashers

Dishwashing machines can be better for the planet than slogging over the sink with a sponge. The truth of this has taken a long time to ‘sink in’. Perhaps because it seems too good to be true.

Since the early 1990s, dishwashers have had a ‘trickle up’ effect – year on year an extra 1 or 2% of UK households have opted into having a machine do the washing up for them. The latest figures from 2018 show that 49% of UK households now have a dishwasher, meaning that it might soon be the first time ever that it’s more common to have a dishwasher than not.

Dishwasher appliances occupy a big chunk of space in the kitchens of these households, and several brands are now filling that space: 36 are reviewed in this guide, yet nearly half of these brands are owned by just 5 companies (Bosch, Electrolux, Haier Group, Koç, and Whirlpool).

We look at the commitment to the environment and energy efficiency of these big brands and how you can make sure you are being as eco as possible with your dishwasher and your handwashing.

Handwashing versus dishwashing: Which is better?

Studies tend to conclude that dishwashers are better for the environment than washing up by hand. Overall using a dishwasher results in lower carbon emissions, even if you add in its embodied emissions. Handwashing generally uses more water than dishwashers, resulting in more greenhouse gas emissions from distribution, and more energy use from heating up the water.

Do dishwashers use a lot of energy?

How much energy is used to wash dishes depends on factors including:

• The energy rating of the dishwasher.
• The cycle setting used.
• How full the dishwasher is.
• If handwashed, what technique the individual uses.

Table 1: Cost and energy usage of handwashing and machine washing

*The CDA D-rated model (CDI6241) is due to be launched mid-June 2021. Until it’s retailed no official price has been set – but CDA confirmed in May 2021 that it will likely cost around £400.
**Based on average of 12 place settings, 3 times per week for 12 years. According to the Department for Business, Energy & Industrial Strategy (BEIS) the average cost for standard electricity in the UK in 2020 was 17.4p/kWh
Note: Other than CDA, brands selected were a Best Buy, Recommended Buy or Brand to Avoid. If a brand made several products with the same energy rating, the lower cost model was opted for. If the model was retailed on several websites, the lower price was opted for. Prices reflect an estimate of prices at the time of writing.
Note that if best practice was followed for washing 14 place settings using the same amount of water as for 8 settings, the kWh would be improved.

Best practice for washing dishes by hand (while still cleaning effectively) is to soak and scrub dishes in one bowl of hot water, then rinse them in cold water.

Otherwise, as the table above clearly shows, washing up by hand uses more energy than using a machine, although it is by far the cheapest option overall.

Washing by hand requires more energy per place setting than machine washing, even with the least efficient dishwasher model we reviewed in the table.

This table does not include the initial embedded energy costs for dishwashers (or sinks/taps). However, one study suggests that materials and manufacture constitute only a fraction of the energy used over the lifetime of its use (less than 10%). Mike Berners-Lee comes to the same conclusion in his book, How Bad Are Bananas?

If a dishwasher is well looked after, it can last up to 16 years.

How much water does a dishwasher use?

A 2020 article published in the Environmental Research Communications journal calculated the average water consumption figures for manual dishwashing as shown in the table below.

The table below shows how even best practice handwashing consumes significantly more water than machine dishwashers.

Washing dishes with the tap constantly running uses 20 times more water than the most water-efficient machines.

Table 2: Water usage of handwashing versus machine washing

By far the worst option for the planet and your pocket is to wash dishes using a running tap.

One study asked participants to wash up dishes by hand and examined their technique:

• 16% demonstrate best practice
• 41% ran the tap constantly
• 43% used a combination of good practice and running the tap

Eco friendly dishwashers

Energy efficient dishwashers

In this guide, the most efficient dishwashers have a B-rating under the new energy label system. No dishwashers were efficient enough to get an A-rating under the new energy label rating. B-rated dishwasher models scored half a product sustainability mark. Smeg, Bosch, Hotpoint, Neff and Siemens all offered a B-rated model.

However, all of these brands also sold models that were rated E or F. Only 2% (one model of its range of 35) of Hotpoint dishwashers were B-rated. This rises to 3% of Bosch, 5% of Smeg, 20% of Neff, and 19% of Siemens models. Siemens had the largest range of B-rated models, offering four in total.

Several brands didn’t offer any models above an E-rating, or still used the old energy ratings system when we checked in May 2021. These brands were Lamona, Montpellier, Swan, Essential, Amica, Blomberg, Gorenje, Logik, Candy, Baumatic, Fisher & Paykel and Hoover.

Best Buy Miele offered nine models in total, seven of which were C-rated, with its least efficient model rated E.

Minimising your dishwasher’s impact

Consumers can easily accidentally increase energy usage by 50% by pre-rinsing dishes, incorrectly loading the appliance, or choosing the wrong cycles.

Choose the eco cycle

Which? states that, on average, its independent tests show that eco programs use 30% less energy and water than regular programs. We therefore recommend always using the eco mode, which now comes as standard even on basic modern dishwashers.

These use lower temperatures and less water so cycle lengths are longer in order to guarantee a thorough clean.

Which? also states “Energy labels are based on a manufacturer nominated program – so always the eco program. But this doesn’t give a good indication of how efficient the machine will be on its auto or normal program.”

Therefore, if you buy a product with a B-rating, but use the regular setting, it might not be any better than a lower-rated model. A 2017 study showed that 87% of the consumers wrongly believed that the energy label covered more than just the most efficient program.

Some dishwashers have a ‘half-load’ setting, but this feature can still use up to 90% of the water and energy used by a full load.

One study tested this on a Miele dishwasher. It showed that if a consumer used the automatic programme instead of the eco cycle, water use would be 44% higher and energy use 62% higher. The intensive/fast wash was even more extreme – water use would be 55% higher, and energy use 73% higher.

Avoiding selecting options such as heated drying can decrease life cycle GHG (greenhouse gas) emissions for machine dishwashing by 11%.

To rinse or not to rinse before loading?

Choosing not to pre-rinse can decrease life cycle GHG emissions for machine dishwashing by 3%. In Sweden, 51% of consumers pre-rinse each item quickly, compared to just 10% in Germany. The best option is to avoid rinsing and instead scrape your pots before loading.

Maintenance and usage tips

At risk of stating the obvious, the following tips are relevant for eco conscious dish washing:

• Scrape as much food off dishes as possible before loading.
• Ensure it’s full before turning it on, but ...
• Avoid overcrowding the dishwasher.

Less obviously, The Spruce suggests that empty dishwasher space can be filled with cleaning sponges, fridge shelves, vases, toothbrush holders, soap dishes, plastic hairbrushes, (non-wooden) garden tools, flowerpots, grill grates, flip flops or bins.

How ethically and environmentally responsible are dishwasher brands?

In our score table, every brand in this guide lost a whole mark under the Human Rights category. There are several reasons for this, which included: failing to create an adequate conflict minerals policy; operations in oppressive regimes; and supplying the military.

All brands also lost at least half a mark under Habitats & Resources which was also often due to inadequate conflict minerals ratings.

The majority of dishwasher brands scored worst ratings for Supply Chain Management. Only three scored a best rating. These were Miele, John Lewis and Bush. However, Bush (owned by Sainsbury's) came in last on the Ethiscore table and John Lewis also scored poorly.

Many brands lost half a mark for excessive director’s pay. Samsung’s highest paid director received an astonishing £31 million in 2019, while Siemens reported that all eight of its managing board received over £1 million in annual remuneration.

Environmentally responsible companies?

We also researched how well companies are taking responsibility for their environmental impacts.

15 brands received a worst rating for their Environmental Reporting, and 20 received a middle, while Samsung was the only brand to receive a best rating (though it received an overall Ethiscore of just 3.5).

Only one brand (IKEA) received a best rating under the Climate Change column. Miele, AEG, Electrolux, Hotpoint, Zanussi, Indesit, Whirlpool, and Samsung scored middle ratings, while all other brands (75%) lost a whole mark in this category.

Dishwasher brands

Big brand owners in the dishwasher industry are concentrated in five companies: Electrolux (AEG, Electrolux, Zanussi), Bosch (Bosch, Gaggenau, Neff, Siemens), Haier Group (Hoover, Baumatic, Candy, Fisher & Paykel), Koç (Beko, Blomberg, Grundig) and Whirlpool (Hotpoint, Indesit, Whirlpool).

Bosch is the leading UK dishwasher brand by a long stretch – over 5 million people in Britain had a Bosch dishwasher in 2019. This is more than twice that of its closest competitors Beko and Hotpoint (each with around 2.25 million users).

Since the last guide to dishwashers, we have removed the following brands: Britannia, Daewoo, KitchenAid, Leisure, LG, Maytag, New World, Servis and White Knight. These had either discontinued their dishwasher models, or the models no longer appeared readily available to buy in the UK. We have added the following brands: Amica, CDA, Kenwood, Logik and Montpellier.