When the time comes to clean his pants, he says, he wears them into the shower and washes them with soap, much like you’d wash your legs.

That’s not a daily thing, mind you. It’s only when the jeans are “really gross.” Otherwise, he says, he’ll do a spot clean if, for instance, he spills something on his jeans.

The advice comes nine years after Bergh seemingly suggested people never wash their jeans at an event (something he denies saying). But washing jeans, he tells CNBC, impacts the shape and color of the jeans, hurting their appearance and shortening their life span.

“True denim-heads, people that really love their denim, will tell you to never put your denim into a washing machine,” he said. “So that’s what I do.”

There are also ecological reasons to avoid tossing your Levi’s in the washer.

While the jeans are cotton, they use a good bit of water in the production of the pants—and washing them after every few wears makes the environmental footprint of the jeans progressively larger.

A 2021 scientific study found microfibers from blue jeans, which enter the environment from washing machine wastewater, have been detected in lake sediment as well as Arctic areas of Canada.

“Blue jeans, the world’s single most popular garment, are an indicator of the widespread burden of anthropogenic pollution by adding significantly to the environmental accumulation of microfibers from temperate to Arctic regions,” the report read.