Washing machines: How we test washing machines
How Which? puts washing machines to the test
The Which? test program for washing machines includes more than 300 tests on washing, rinsing, convenience issues and noise, which enable us to recommend the Best Buy washing machines that won't let you down. We go to great lengths to design thorough and rigorous tests. For example, we enlist the help of Tomahawk the husky to test washing machines that have a 'refresh' cycle, measuring how well this removes dog odour from Tomahawk’s bedding.
Video guide: what makes a Best Buy washing machine
You can see the differences between a good and bad washing machine and find out what it takes to become a Which? Best Buy in our video.
If you're shopping for a washing machine, go straight to our independent washing machine reviews.
Washing machine cleaning
For cleaning, we test how each washing machine copes with shifting tough stains such as olive oil, grease, ink and cosmetics from a specially prepared cloth that’s put into the drum with T-shirts, sheets and other items.
After the wash is finished, we measure how much light is reflected from stains on the special cloth using a spectral photometer, so we can work out exactly how much of the stain has been removed.
Rating washing machine noise
We use a panel of five experts to test how noisy washing machines are during their wash and spin cycles.
The Which? experts don't just look for how noisy a washing machine is, but also rate how intrusive and annoying the sound is.
Rinse test for washing machines
To measure how well each washing machine removes detergent during the rinse cycle, we take freshly rinsed washing from the machine, just before the spin cycle, and spin it in a super-fast spin dryer. This dryer spins at 2800rpm, roughly twice as fast as a typical washing machine.
After the spin, we collect water from the clothes and measure how alkaline it is compared with the alkalinity of tap water used in the wash. Detergent is alkaline, so the greater the increase, the poorer the washing machine is at rinsing.
For many washing machines we test, rinsing is an Achilles heel – there are only a few that produce good results on different wash programs.
Washing machine energy use
We don't just take a manufacturer's word for it when they say their washing machines are energy efficient. We run our own tests to calculate how much water and energy each machine uses, and work out how much you would pay to use each machine on the main cotton wash four times a week for a year.
Washing machine program choice
The Which? tests are designed to mimic the use of a washing machine in the home. By consulting our members, we've been able to build up a picture of how most people use their washing machine.
Though many washing machines include 15 or more wash programs, we know in reality most people stick to using the main cotton wash, the short program and the easy-care wash.
Each program is chosen in agreement with our independent lab testers after careful consideration of the controls and the manufacturers’ instructions, so we can be sure we accurately reflect the performance of washing machines.
The criteria we use are based on our experience of testing hundreds of washing machines each year.
Modern washing detergents enable most people to wash at 40ºC for almost all washes, so we only test at this temperature because this helps to protect the environment by reducing the amount of energy and water used by doing the washing.
We currently do a full load wash and the main easy-care cycle at 40ºC.
Washing machine special features
Often washing machines come with interesting or innovative new programs and features that we can test out in our lab. These can include express programs for cleaning clothes quickly; 'refresh' programs which claim to remove odours or freshen-up dry-clean clothes without water; and eco programs that claim to use less water and energy.
To test refresh programs, we call in the help of our canine friend Tomahawk the husky. We use woolly jumpers that Tomahawk has slept on for eight hours to see how well these programs remove his scent.