Look, we all know we’re supposed to be washing our clothes cool. For the sake of the planet, and our energy bills, defaulting to 30C instead of higher temperatures can save 40% of the energy used each year, according to the Energy Saving Trust. The EU has even made it compulsory since 2013 for all new machines to have a 20C option.
Still, it can be tempting to let the dial slip back to 40C for old times’ sake, or stick on a cheeky 60c wash when faced with serious stains, feeling we need to crank up the heat. But does hotter really equal cleaner? Or more hygienic? And, more importantly, which do our clothes prefer?
The first thing to know is that not all stains are created equal. For protein-based stains – such as egg, milk, ice-cream, avocado, mud, blood and all other bodily secretions – hot water can actually make the problem worse, causing the substance to coagulate and effectively “cook” into the fabric. Instead, cool water with an enzyme-based detergent does a much better job of flushing the stain away.
Other common stains such as berries, tomatoes, coffee and ink can tolerate higher temperatures, but that doesn’t mean they can’t also be shifted at lower ones. In fact, most modern detergents are designed to remove stains at 30C – though Ecover’s Bio Laundry Liquid can fight stains at as low as 20C. In bio formulations, enzymes do the hard work of breaking down stain molecules, but water above 55C can actually denature those enzymes, making your detergent less effective. Even non-bio products, such as some of Ecover’s detergents with biodegradable ingredients, are rigorously tested to make sure they’re powerful enough to wash cool.
The only stains that might require warmer water are oil and grease, but these can be banished faster with some household tricks: coat the stain with talcum powder, cornflour or dry shampoo (those travel-size cans have saved more than a few of my holiday outfits) to absorb the oily excess, followed by a spot wash with washing-up liquid – which is designed, after all, to cut through grease.
You might be worried that a cool wash is unhygienic, but the truth is that hot water alone is no guarantee of cleanliness; some bacteria and viruses can survive even washes of 60C and above. A good detergent is an important weapon at all temperatures, but especially cooler ones, because they use surfactants to physically break down and slough away microbes. Unless we’re talking about a sickness bug, a nappy explosion or the after-effects of a Tough Mudder challenge, it’s best to take each load on a case-by-case basis.
Then there are the benefits for your wardrobe. Washing low can help your clothes last longer and look better, beyond just shifting the remnants of last night’s ragu.
Heat breaks down dyes in fabric, causing clothes to fade faster – particularly black, which (PSA for the goths) only needs to hear the words “hot wash” to start turning grey. Researchers at the University of Leeds compared 30-minute cycles at 25C and 85-minute cycles at 40C, and found that the cooler, quicker cycle reduced dye release by 74% and halved the amount of microfibre shedding.
That’s great news for the outfits we’d like to be wearing for years to come. A report by home appliance brand Electrolux shows that a cotton T-shirt washed at 30C for 59 minutes will last more than 50% longer than when washed on a 40C cycle. And if that isn’t enough incentive, washing cool can even reduce creasing, because heat makes fabric fibres more malleable.
In short? It’s worth dialling things down whenever you can. As any cold-water swimmer will tell you: once you form the habit, the benefits can be huge.
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