Although it was once true that washing laundry at high temperatures was more effective, that’s no longer the case. Advances in washing machines and detergent technology mean that most clothes can now be cleaned effectively at temperatures as low as 15°C (59°F).
For starters, modern washing machines are designed with cooler washes in mind.
New drum designs and more sophisticated tumble sequences agitate clothes more effectively, ensuring that dirt and stains are removed mechanically, without the need for high temperatures.
Laundry detergents have also improved in recent decades. Detergents contain a mixture of cleaning agents, including surfactants and enzymes.
Surfactants work by grabbing dirt particles and oils from your laundry and pulling them into the wash water. Scientists have found that shorter surfactant molecules are more effective in cold washes, so many detergents now use this type.
Anti-redeposition agents work alongside surfactants to keep dirt suspended in the water, so that it doesn’t stick to other clothes in your wash.
Dirt particles become less soluble at lower temperatures, so modern detergents are also formulated with anti-redeposition agents.
Additionally, new detergent formulas use enzymes that have been isolated from bacteria living in cool climates, such as Iceland, meaning they clean your clothes most effectively at around 15°C to 20°C (59 to 68°F).
There are lots of benefits to lowering your wash temperature. Heating water accounts for about 90 per cent of the energy a washing machine uses, so washing at lower temperatures can reduce your electricity bill.
Washing in hot water causes wear and tear on fabrics, so cooler washes also mean your clothes will last longer and they’ll shed fewer microplastics.
There are some exceptions, however. For clothing that needs to be sanitised, such as cloth nappies or medical scrubs, hot water is still the best thing for the job.
This article is an answer to the question (asked by Theo Hayes, Leeds) 'What's the best temperature to wash laundry at?'
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