Exactly How Often You Should Wash Your Clothes—According To A Stink Scientist

Got laundry to do this weekend? Read this first.

April 7, 2017
washing clothes
Martin Poole/getty

According to Rachel McQueen, a textile scientist and associate professor in the University of Alberta’s Department of Human Ecology, most people wash their clothes way too often. “I think what’s happening in this hygiene-focused world now is that it’s just become a habit,” she says. “People wear a pair of jeans or a sweater once and think it’s loaded with bacteria.”

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It isn’t so much that bacteria don’t populate your clothing—they most certainly do. But that doesn’t mean you have to wash your clothes. “It’s a bit overkill because it’s their bacteria,” McQueen says. “It’s supposed to be on your skin. And so if it’s on your clothing, and your clothing puts it back in contact with your skin, that’s just where that bacteria is supposed to be.”

McQueen should know. She’s one of the only researchers in the world whose studies focus on examining how skin microflora grows in textiles, and how odorous molecules interact with the fibers. In other words, she studies stinky clothing.

And unless you work in a hospital or with immune-compromised individuals, McQueen adds, bacteria of this sort isn’t a huge problem. Of course, she’s not advocating that you dump your washer altogether. But, she says, there are numerous reasons to resist the urge to wash your clothes so often.

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washing machine
You'll Save Water And Energy

First and foremost, water and energy usage. The Alliance for Water Efficiency reports that the average American family washes almost 400 loads of laundry a year, which accounts for up to 40 percent of overall water consumption in a typical four-person household.  Clothes dryers, per Energy Star, account for about 6 percent of home electricity use. (Here are 9 ways to save water in your home.)

stack of jeans
Your Clothes Will Last Longer

And then there’s the wear and tear on your favorite items. Each wash cycle degrades the fibers of your clothing, so not only are you paying more for the water and the electricity or gas, you’ll also be paying to replace those khakis and shirts sooner.

Consider denim — something McQueen has done quite a bit, as it’s one of the most popular garments worldwide. Excessive laundering means faster thinning of the fabric and loss of color, especially in areas like the thighs and butt that already rub when worn.

McQueen conducted a less-formal study with a student of hers who wore a pair of jeans without washing them for 15 months and one week.  They tested the bacteria growth, then washed, had him wear for two more weeks, and tested again. The results? The counts from their bacteria scrapings were virtually the same — and even though McQueen expected to find some lower intestine bacteria such as E. coli, she didn’t.

Bottom line? If jeans worn for a year without washing are about as dirty as jeans worn for two weeks, you can definitely wash your jeans less often than you do now.

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smelly sock
But If It's Smelly, Wash It

But, you might say, my clothes actually do stink after one wear. “Clothing that smells? Wash it,” McQueen says. “That's a pretty legitimate reason. But if it doesn’t, why do you need to wash it again?” (Most B.O. is innocuous, but some isn’t—here are 5 body odors you should never ignore.)

“I'm not the sort of an advocate for, ‘Oh well, I think you should wear your underwear three times before you wash it,’” McQueen says. “I do think, again, there are hygienic or smell reasons for wanting to do that on a daily basis. … If somebody has strong body odor, they may actually need to wash their T-shirts every wear. But it doesn't mean they have to wash their sweater out every time, because their sweater might have that additional layer of fabric in between.” (Here are 5 amazing things you didn’t know about your wool sweater.)

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camping trip
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Wear Natural Fibers

If your clothes do smell after one wear, McQueen adds, you might reconsider the types of fabrics you’re wearing. Natural fibers, such as cotton or wool, are less likely to stink than synthetics, such as polyester or bamboo rayon.

A natural fiber, explains McQueen, has high absorption power, much like the activated carbon or charcoal found in filters for garbage or compost bins. (Here are 8 healthy uses for activated charcoal.)  “It has that ability to be able to take in and absorb those odorous compounds. And so therefore, if it’s absorbing them, and it's actually in the fiber, it’s not in the headspace for us to smell it.”

Another option is to regularly use natural-fiber base layers. Going commando might appeal to some, but you’ll pay a lot less long term if you’re washing underwear daily, rather than your jeans. (For more fixes for problematic body odor, see 6 effective solutions for body odor.)

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At the end of the day, McQueen says, she hopes that people will consider changing their individual habits, even if just a little. If you currently wash everything once a wear, maybe consider letting certain items go three wears. Every small change, she says, helps your wallet and the bigger environmental picture.

As for your jeans? That’s up to you.