More than 60% of Americans still wash their laundry in warm water. It’s a practice that’s as costly as it is environmentally unfriendly. What’s more, it doesn’t make our clothes appreciably cleaner. Here’s why you should make the switch to cold water.

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Illustration by Tara Jacoby.

Given that we all have to do it, it should come as little surprise to learn that laundry exerts a significant global footprint. Of the total energy use and greenhouse-gas emissions produced by a single load of laundry, approximately 75% of it comes from warming the water itself.

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There’s also the cost to consider. According to Consumer Reports, doing laundry in cold water will save you upwards of $60 per year (or more if you live in an area with higher-than-average electricity rates), assuming an average of 300 loads per year. That may not sound like much, but it’s significant when considering the pressure placed across the entire electrical grid.

Think of it this way: If every Las Vegas household switched to cold washing for an entire year, the amount of energy saved could power its famous Strip for nearly a week. If every household across the U.S. switched to cold water for an entire year, that would save the same amount of energy produced by the Hoover Dam in 20 months.

Credit: H.A.M. Phtgrphy/Flickr/CC.

As noted by Leigh Krietsch Boerner at The Sweet Home, “[U]nless you have a really good reason for washing in warm or hot, such as really stinky clothes or cloth diapers, go for cold. It saves energy, and your clothes will last longer.”

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Indeed, cold water is actually good for certain clothes. Lower temperatures protect the dyes, and therefore the color of clothes, while also helping to preserve the fit of the clothes by preventing shrinkage, particularly along the seams. What’s more, some stains, like blood, should only be washed in cold water. Warm water just makes blood stains set in.

So aside from some rare instances, there’s really no reason for you to keep washing your clothes in warm water. The Laundry Goddess offers some practical tips:

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Personally, I have found that you can wash everything in cold water successfully, as long as you follow a few basic rules: Only use liquid detergent, as most powders need warm water to completely dissolve and clean successfully. Use the proper amount of detergent – too little and your wash load will not come clean, and too much will leave a soapy residue behind on your wash.

Also, do not overload the washer; be sure to leave room for items to move around in the water.

Substituting for Warmth

Now all this said, warm water does play an important role in helping to make your clothes clean. Well, provided you use high performance detergents and washing machines — and provided you follow the manufacturer’s instructions. Using too much or too little detergent can result in sub-optimal performance, as can using the detergent at the wrong temperature. Using a standard warm-water detergent in cold water, for example, may not get you the results you want. So, unless you opt for a specifically cold water detergent, you may not notice that the warm water is cleaning better. But the fact of the matter is that you can get just as clean with cold.

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Laundry involves a number of chemical reactions — reactions that go faster at higher temperatures. So, along with chemicals and mechanical energy, the thermal energy produced by warm water helps to get rid of stains, dirt, and residue on our clothing. Until very recently, most detergents were designed with this in mind. Owing to a demand for more environmentally friendly solutions, detergent manufacturers have now found ways to create detergents that work remarkably well in cold water. But to do so, they had to get around some very tricky chemical constraints.

One of the biggest challenges to developing detergents that work in cold water, or regular “tap water,” is that tap water temperatures are inconsistent across geographical locations and seasons. For example, “cold” water in Florida during the summer months is ~80 degrees F, while “cold” water in Minnesota during the winter months can dip as low as ~40 degrees F. Consequently, cold water detergents need to work effectively across a surprisingly large spectrum of temperatures.

To complicate things even further, surfactants — the so-called “work-horse” of detergents — don’t perform as well in cold water. These chemicals, which comprise upwards of 30 to 40% of the weight of detergents, lift and removesstains. They involve a class of chemicals known as linear alkylbenzonesulfates — long chains of a chemical called a dodecane.

Credit: FluffLoveUniversity.

Writing in C|Net, Richard Baguley and Colin McDonald explain how surfactants work:

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[Dodecane] readily forms long chain molecules, quite similar to petrochemicals like oil. Attached to this is a benzene ring, with a sulfate molecule attached. These two parts fundamentally disagree about something: how they feel about water. The dodecyl chain hates it, doing all it can to get away from it. The benzosulfate bit, however, loves water and wants to get close to it. Chemists call these properties hydrophobic (water-hating) and hydrophilic (water-loving), and this conflicting nature is what makes detergents so powerful. Dodecyl chains hate water, but like each other, and also like other chemicals like fats, sugars, proteins and others. In other words: all of the things on your clothes that you want to get off. Dodecyl chains also like each other: give them a chance, and they will gather together and complain about how much they hate water.

It’s this tension that works to clean our clothes; the hydrophilic part mixes with the wash water while the hydrophobic part of the molecule lifts up and absorbs stains and dirt so they can be rinsed away. Surfactants work the same way when exposed to different temperatures, but as Mary Johnson, Fabric Care Principal Scientist for Tide and Downy, told me, surfactants “can become super-sluggish in colder water temperatures – leading to stained and dingy clothes.”

To get around this problem, Procter & Gamble chemists — who get the credit for developing this innovation — created a specially formulated surfactant system, which can be found in Tide Cold Water Clean and Tide PODS. Their system overcomes these limitations in three ways. Here’s how she explained it to me over email:

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1. We use a variety of different surfactant types and within each type we use a variety of chain lengths. This makes the surfactant system super-fast and super-responsive across a broad range of temperatures — even in temperatures as cold as 40 degrees F.

2. We also use polymers – long chain molecules – at high concentrations that act as cleaning boosters to help remove more stains – even greasy stains in cold water.

3. We use enzymes to help break up stains which can then be lifted away by the surfactants.

Indeed, enzymes are another important component of modern laundry detergents. Enzymes, which are comprised of biological components, break down stains that are otherwise hard to remove with conventional surfactants alone. Fascinatingly, P&G uses enzymes that were inspired by the evolved systems of organisms found in cold ocean water — systems that don’t get sluggish when exposed to cold water.

Cellulase 1JS4, a common enzyme found in detergents Credit: Pratulka/cc.

“In addition to using a wide variety of surfactants while adding polymers and enzymes – we also increased the amounts of these ingredients to... clean in even the coldest wash temperatures,” added, Johnson, who says Tide’s Cold Water Clean works better in cold water than its base Tide liquid product.

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In addition to the products already listed, other cold water detergents include Arm & Hammer Cold Water, and Purex Coldwater. Encouragingly, washing machine manufacturers are getting involved as well; Whirlpool’s Maytag Bravos XL is a washer designed to work with cold-water detergents.

But as noted, you may not need to resort to these specialized products in most instances. So what are you waiting for? It’s time to start cleaning your clothes in cold water.

Sources: New York Times | Consumer Reports | CNet | Dr. Chemical (2)| BBC


Contact the author at george@io9.com and follow him on Twitter