Study Finds Unwashed Jeans for 15 Months Show Similar Bacteria Levels

Jeans are one of the most universally beloved wardrobe items worldwide. They look casual with a T-shirt and work for semi-formal occasions when paired with a shirt or jacket. The challenge lies in washing them. Since a single wash can alter the distressing or color, the notion that "jeans don't need frequent washing" has become widely accepted. But do they really require less laundering than other clothes?

Many jeans manufacturers advise that frequent machine washing can damage the fabric and cause fading. Spot cleaning stained areas or airing out the garment are common recommendations. Denim is prone to color bleeding, and aggressive spin cycles can accelerate dye loss. Stretch denim blends are also noted to lose elasticity with excessive washing, leading to fit distortion.

Research supports the "less washing" claim. The New Zealand Herald recently highlighted an intriguing experiment conducted by Canadian researchers. Professor Rachel McQueen's team at the University of Alberta said curiosity about a student who rarely washed his jeans inspired the study.

The researchers compared bacteria levels on jeans worn for 15 months without washing against jeans worn for two weeks before washing. The results defied expectations. Bacteria found on both pairs were at levels commonly present on the human body. Statistical analysis showed no significant difference indicating that longer washing intervals led to explosive bacterial growth.

Josh Le, a 20-year-old male participant, reportedly never washed his jeans to preserve their natural creases and faded look. Researchers measured contamination levels on his jeans and compared them with jeans washed after two weeks of wear. Professor McQueen said, "We expected the jeans unwashed for 15 months to be much dirtier, but bacterial counts were not significantly different." However, the crotch area—where friction is highest due to body structure—showed the highest readings, roughly 8,000 to 10,000 bacteria per square centimeter. No harmful bacteria were detected, she added.

This does not mean jeans never need washing. Experts emphasize that hygiene depends on activity level and environment. Washing is necessary after heavy sweating or exposure to contaminants. If odor or stains develop, laundering benefits both hygiene and garment maintenance.

When washing is needed, technique matters. For spot cleaning, apply neutral detergent to the soiled area and gently rub. For full washes, close zippers and buttons, then use cold water on a gentle cycle. Keep spin cycles short—under three minutes—and air-dry jeans inside-out in the shade rather than using a dryer to minimize bleeding and distortion.