Clothes left sitting in a finished wash cycle start developing a sour, musty smell surprisingly fast. The fix is straightforward: rewash them with an odor-neutralizing agent like white vinegar or baking soda, using the hottest water the fabric allows. But understanding why the smell happens and how to prevent it will save you from dealing with it again.
Why Wet Clothes Start to Smell
The musty odor isn’t just “mildew” in a vague sense. Research published in Applied and Environmental Microbiology identified a specific bacterium, Moraxella osloensis, as the primary culprit. These bacteria thrive in the warm, damp environment of a closed washing machine and produce a fatty acid compound that creates that distinctive wet-dirty-dishrag smell. The bacteria feed on residual body oils and organic matter left on fabric, and a sealed washer drum is their ideal breeding ground.
The clock starts ticking as soon as the wash cycle ends. Clothes can generally sit in the washer for 8 to 12 hours before odors become noticeable. By 24 hours, you’re likely dealing with visible moisture spots and a smell that won’t go away with simple air drying. If your clothes have been sitting overnight, they probably need a rewash. If they’ve been sitting a full day or more, you’ll want to use one of the stronger methods below.
The White Vinegar Method
White vinegar is the most reliable household fix for musty laundry. It’s mildly acidic, which helps kill odor-causing bacteria, and it breaks down the organic compounds producing the smell. Add half a cup of white distilled vinegar to the fabric softener dispenser or pour it in manually just before the final rinse cycle. Then run the load again on the hottest setting your clothing labels allow.
If the smell is strong, you can pause the machine right before the final rinse, pour in the vinegar, and let the clothes soak for 15 to 30 minutes before resuming the cycle. The vinegar smell dissipates completely once the clothes dry. Don’t combine vinegar with bleach in the same load, as the mixture produces toxic fumes.
The Baking Soda Method
Baking soda works differently from vinegar. It’s alkaline, so it neutralizes the acidic compounds that produce sour and sweaty odors rather than just masking them with fragrance. Add half a cup directly to the drum with your smelly clothes and run a full wash cycle with your regular detergent. This is especially effective for sweat-related odors, since the compounds in perspiration are acidic.
For particularly stubborn smells, you can use vinegar and baking soda in the same wash, but add them at different stages. Put the baking soda in the drum at the start of the cycle and add the vinegar during the rinse. Adding them simultaneously causes a fizzy reaction that neutralizes both ingredients before either can do its job.
When You Need Something Stronger
If vinegar and baking soda don’t fully eliminate the odor after one rewash, oxygen-based bleach (the active ingredient in products like OxiClean) is the next step up. It releases hydrogen peroxide when dissolved in water, which kills bacteria and breaks down organic residue without the harshness of chlorine bleach. Dissolve the recommended amount in warm water, soak the clothes for one to two hours, then wash normally. Oxygen bleach is color-safe for most fabrics, though you should check the label on delicates.
Chlorine bleach is more powerful and will kill virtually anything causing the odor, but it’s only suitable for white fabrics and can damage elastic, spandex, and many synthetic materials. If you’re dealing with white towels or cotton sheets that have a deep-set musty smell, a standard bleach cycle will handle it. For colored clothing, stick with oxygen bleach.
Laundry sanitizer products designed to be added during the rinse cycle use quaternary ammonium compounds, which destroy bacteria by breaking apart their cell walls. These are effective against a broad range of pathogens and work in cold water, making them a good option for delicate fabrics you can’t wash on hot.
Drying Makes a Difference
How you dry the clothes after rewashing matters almost as much as the rewash itself. Sunlight is a natural disinfectant. Ultraviolet rays kill remaining bacteria on fabric surfaces, and the heat accelerates evaporation so bacteria don’t have time to recolonize. If you can line-dry outdoors, even for a portion of the drying time, it helps.
If you’re using a dryer, run it on the highest heat setting appropriate for the fabric and make sure the load is fully dry before you pull it out. Removing clothes while they’re still slightly damp and folding them into a drawer recreates the same warm, moist conditions that caused the problem in the first place.
Clean the Machine Itself
Sometimes the smell isn’t just in the clothes. If your washing machine has its own musty odor, it’s reinfecting every load you run. Bacteria and mold form a sticky biofilm in several hidden spots: the rubber door gasket on front-loaders, the detergent dispenser and its housing, the drain pump filter, and inside corrugated drain hoses.
Pull back the rubber gasket on a front-loader and wipe the folds with a cloth soaked in vinegar or diluted bleach. Remove the detergent dispenser drawer entirely (most slide out with a release tab) and scrub it in the sink. Run an empty cycle on the hottest setting with two cups of vinegar or a commercial washing machine cleaner tablet once a month. For top-loaders, the same empty hot cycle with vinegar works, though biofilm tends to accumulate less since top-loaders drain more completely.
Preventing the Smell Next Time
The simplest prevention step is also the most effective: move your clothes to the dryer or a drying rack as soon as the wash cycle finishes. Setting a timer on your phone takes five seconds and saves you from rewashing an entire load.
Leave the washer door ajar between loads. A closed door traps moisture inside the drum, creating the exact conditions bacteria and mold need to colonize the machine. This is especially important for front-loaders, which seal tightly. Even cracking the door an inch allows airflow that dramatically reduces internal humidity.
Use the right amount of detergent. Excess soap leaves a residue on clothes and inside the machine that becomes food for bacteria. If you’re using a high-efficiency machine, use HE detergent and measure it rather than eyeballing. Liquid fabric softener also leaves a coating on fabrics that can trap odors over time. Vinegar in the rinse cycle softens clothes without the residue.
If you know you won’t be able to move the clothes promptly, some machines have a “fresh hold” or “fan dry” setting that tumbles the load periodically or runs a fan to keep air circulating after the cycle ends. Using this feature can buy you several extra hours before odor sets in.