If your clothes are smelling musty or mildewy even after washing, you aren’t alone. It’s one of the most common complaints in Australian laundries – and the solution is simpler than you think.
New research published in the journal Antibiotics has revealed why your laundry smells bad: cold washes combined with liquid detergents create the perfect breeding ground for odour-causing bacteria. While 30°C cycles are better for your clothes and the environment, they also allow germs to survive and multiply in your washing machine.
Why your clothes smell musty (even after washing)
In the published paper, scientists tested washing machines across multiple countries, collecting samples from 15 key contamination points inside each machine, including the detergent drawer, door seal rubber ring, drum, filter, pump, and hoses. They found that 30% of the drums, rubber seals, and detergent drawers harboured odour-causing bacteria in biofilms.
To understand how different wash conditions affected microbial survival, they compared washing cycles at various temperatures (from cold water up to 60°C) using both powder detergents containing bleach and liquid detergents without bleach. The team also tested fabric samples, including cotton and polyester.
What the study found
The study revealed that washing at temperatures below 30°C with liquid detergents (which don’t contain bleach) resulted in significantly lower bacterial reduction than washing at 40°C or above with powder detergents containing bleach.
So while 30°C washes are eco-friendly and save money on power bills (important for Aussie households), they’re not great for removing bacteria from your dirty clothes.
Why do some fabrics smell worse than others?
Polyester fabrics were found to retain more bacteria and develop more pungent odours than cotton.
Why powder detergent works better than liquid
Powder detergents are more effective than liquid detergents at killing odour-causing bacteria because they contain oxygen bleach, a key ingredient that kills bacteria. Liquid detergents and pods can’t contain bleach because it breaks down when stored in liquid form.
How to stop musty-smelling laundry
The researchers acknowledge the dilemma: lower temperatures save energy but reduce hygiene. The solution? Be strategic about when you use cold washes.
Here are the laundry tips they suggest, which are especially important during the Australian summer, when humid conditions make bacterial regrowth more likely:
- Wash towels, bedding, and gym clothes at 60°C minimum
- Use powder detergent with oxygen bleach for regular loads, or add hydrogen peroxide if using liquid detergent
- Save 30°C washes for lightly soiled delicates—everyday laundry needs more heat
- Clean your washing machine monthly with a 90°C empty cycle to prevent biofilm buildup
- Tumble dry when possible—the study found air drying can allow bacterial regrowth, especially in humid conditions
Add a disinfectant to your load of washing
Additionally, researchers say you can add a disinfectant to your load of washing to reduce bacteria.
“Hydrogen peroxide and peroxyacetic acid are environmentally friendly disinfectants and have broad-spectrum antimicrobial activity, low toxicity, high efficiency, and ease of use,” they write.
“Fabrics repeatedly washed in a household washing machine using a liquid detergent with the addition of a 3% stabilised hydrogen peroxide solution were found to achieve disinfection activity but only if the solution was added in the main wash.”
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