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Washing machine temperature guide

By Adrian Porter

Find out what happens to your clothes and bills when you change your washing machine temperature to 30, 40, 20 or 60 degrees.

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Many people use 40ºC wash programmes almost exclusively these days, and the current trend is to use even lower temperatures to save energy. Some detergents are designed to work best at lower temperatures, so you can get good cleaning results in cooler water.

But while clothes may come out lovely and clean, you cannot rely on temperature alone to kill off germs that may be in your laundry – and it’s the same at 60ºC. 

Washing at low temperatures all the time can also lead to a build-up of grease or mould on your washing machine's door seal and inside the washing machine's detergent drawer. Some people have also told us about musty smells caused by low-temperature washes.

Manufacturers advise doing at least one high-temperature wash, known as a service or maintenance wash, at 60°C or above, each month, to maintain and clean out a washing machine.

Removing and cleaning the detergent drawer and wiping round the rubber ring with light bleach cleaners or sprays will also reduce problems.

Some washing machines will do a much better job of cleaning stains than other, no matter what temperature you wash at – see our washing machine reviews to find the best.

Washing at 20°C

Since 2013, all washing machines in the UK have been required to have a 20°C option visible on the control panel to help save energy. But what happens to cleaning power and running costs at this temperature?

When we tested machines on the 20°C cotton program, we found that turning down the temperature from 40°C dramatically reduced running costs – by an average of 66%.

And we found that cleaning power is only slightly worse than at 40°C, with just an olive-oil-based stain not washing out as well.

Using 20°C instead of 40°C could reduce running costs by 66%

Benefits of washing at 30°C

More than a quarter of Which? members use a 30°C program on a regular basis. As you might imagine, it's the recommended setting for a lot of delicate clothes, such as wool and silk – always check the label first though. 

Lower temperatures are also good at helping to preserve colourfully dyed fabrics, although a good quality laundry detergent can help with this, too. 

Similar to the 20°C cotton programs we tested, it was the olive-oil-based stain that didn't wash out as well at this temperature when we ran tests. More general soiling was also lifted compared with washing at 20°C.

Costs are slightly higher for washing at 30°C compared to 20°C. When we tested the 30°C cotton program, we found that running costs are reduced by about 46% compared with the 40°C program.

Difference between washing at 40°C and 30°C

While a 30°C program is good for delicate fabrics, a 40°C wash is ideal for more hardy fabrics. It’s suitable for cotton, linen or viscose, acrylics, acetate, wool mixtures and wool/polyester blends – in other words, most everyday items. This is possibly why it is the most common wash temperature used by Which? members. 

As most Which? members we asked frequently use the 40°C temperature setting, we base our testing on the 40°C cotton and synthetics wash programs.

Most Which? members wash at 40°C, so we base our testing on the 40°C cotton and synthetics wash programs.

Washing at 50°C

This wash is suitable for polyester/cotton mixtures, nylon, cotton and viscose, but with modern detergents most people find 40°C adequate for their needs.

Cost of washing at 60°C

The 60°C program generally delivers slightly better cleaning than the 40°C program, especially when it comes to greasy stains, and is ideal for bedding and towels. But it will cost you – running costs increase by more than half if you wash at 60°C as opposed to 40°C. 

You might be washing at 60°C because you've heard it kills bacteria. The temperature on its own doesn't. Some bacterial spores and viruses are resistant to washing at 60°C. You need to combine your 60°C wash with a good detergent to blast that bacteria. 

Discover the best detergents for removing stains and keeping your whites bright by visiting our laundry detergent reviews. 

We've also taken a closer look at some washing machines' 60°C cotton programs, and discovered that two thirds didn't actually reach 60°C. For more on our findings and how it affects your cleaning, see our guide to washing at 60°C.

Does washing at 90°C kill bacteria?

This is the hottest wash program you’ll find on most machines and is only suitable for some items, such as white cottons and linens – a lot of washing labels won't recommend washing such a high temperature. 

As to whether washing at 90°C will actually kill bacteria, the NHS website states that you should wash underwear, towels and household linen at 60°C to prevent the spread of germs, but says nothing about washing at as high as 90°C to kill bacteria. It also says that you should use a bleach-based product, such as washing power. As mentioned above under 'washing at 60°C', this is key to killing germs, as some bacteria will withstand 60°C temperatures.  

Whatever temperature you decide to clean your clothes on, it's also important to carry out a service wash – a wash at a high temperature without any clothes in the drum – once a month to clean your machine and keep it running well. Check the manual before doing so as it may suggest a specific washing program or temperature.

Other commonly used washing machines programs

Washing machines often have as many as 20 programs for washing, rinsing and spinning. For more information on these other programs, see our washing machine jargon buster.


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