Photo by Stuart Isett for Fortune Brainstorm Green

Chip Bergh wants you to stop washing your jeans. Speaking at Fortune Brainstorm Green conference in Laguna Niguel, Calif., on Tuesday, the Levi Strauss CEO said that while roughly half the water usage happens during jeans production, the other half is consumed at home. Bergh also billed the denim giant as the “ultimate in slow fashion.” “We have a pair of jeans in our archives that are 135 years old, so we are the ultimate in sustainable apparel,” he said. “We build our products to last; if you treat them right, they will last a long, long time—probably longer than most people’s waistlines.”

WORKHORSES

Levi’s also happens to most sought-after brand in secondhand stores like Goodwill, making it the “No. 1 in hand-me-downs,” Bergh added.

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He also spoke about the “Wellthread” initiative, which is currently being test-driven by Dockers, a subsidiary of Levi’s. “The concept is to try to develop a line of product that is sustainable in every single facet of the word,” Bergh said. “Not just environmentally sustainable but socially sustainable and economically sustainable.”

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And if you want to do your bit for the planet, do as “real denim aficionados” do and cut your agua use by washing your denim sparingly, if at all. “These jeans have yet to see a washing machine,” Bergh said, indicating the year-old pair he was wearing onstage. ““I know that sounds totally disgusting, but believe me, it can be done. I have yet to get a skin disease.”

Let’s hope he switches out his underwear regularly at least.

+ Levi Strauss