Levi Strauss helped invent blue jeans in 1873, and ever since then, people have been wondering how often they should wash their 501s.
In an effort to support global water-saving efforts, Levi Strauss & Co. urged buyers in the mid-2000s to wash jeans as infrequently as possible. Back then, Levi Strauss even promoted the idea of freezing jeans as an alternative to washing – a method that scientist Stephen Craig Cary debunked in Smithsonian Magazine.
Most of the bacteria on your jeans probably started growing on your own body, Cary told Smithsonian in 2011.
“I would suggest that you either raise the temperature to 121 degrees Celsius for at least 10 minutes, or just wash them!” Cary said. “The latter surely is the best alternative to save energy.”
A recent Instagram poll of more than 6,500 people, conducted by MarthaStewart.com, found that 57% of respondents washed their jeans after a few wears, while 13% washed them after every single wear. A tiny group totaling 2% admitted that they never washed their jeans, and 29% said they tossed their jeans in the laundry only when they had to.
Real Simple recommends washing jeans after every four to five wears as the best protection against bacteria. But if you’re not a germaphobe, you can pull way back, experts say.
“The less you wash them, the better, especially denim with any elastane (stretch),” Nicole Russo, a private stylist based in New York City, told Real Simple last year. “When you wash your denim, you’re putting it through a beating, and each cycle breaks down the fabric.”
In one informal experiment, a Canadian student went 15 months without washing his jeans. When he and one of his professors tested them, the amount of bacteria growth was similar to levels seen after two weeks.
“I expected to find some bacteria associated with the lower intestine such as E. coli, but was surprised to find there weren’t any, just lots of normal skin bacteria,” his University of Alberta professor, Rachel McQueen, said in 2011. “This shows that, in this case at least, the bacteria growth is no higher if the jeans aren’t washed regularly.”
Unless you’re in construction or doing other heavy-duty work, washing your jeans every 10 wears should be enough, the internet consensus seems to be. Another reason to wash your jeans more frequently might be if you frequently wear them in warm, humid weather.
“Most people wash their jeans way too often,” Patric Richardson, founder of The Laundry Evangelist, told MarthaStewart.com.