How to Get the Musty Smell Out of Towels for Good

To get the musty smell out of towels, run them through a hot wash at 130°F (54°C) or higher with one cup of white vinegar and no detergent, then a second hot wash with half a cup of baking soda, and dry them fully on high heat right away. That two-step strip-and-reset breaks down the odor-causing residue trapped in the fibers.

If that smell keeps coming back, the towels are not the problem. Your wash routine is feeding whatever lives in them. Below, we explain exactly what causes the musty and sour odor, then walk through the reset that actually clears it and the habits that keep it from returning.

Why Do My Towels Smell? The Real Cause Is Biofilm

A musty or sour towel smell is not “dirt” in the way most people picture it. It is a biofilm: a sticky, self-protecting layer of microbes and gunk that clings to the fabric.

That layer is built from several things working together:

• Bacteria, most notably Moraxella osloensis, which is widely identified in laundry science as the primary source of the sour, damp-laundry smell. As it metabolizes leftover organic matter, it releases the volatile compounds your nose reads as “musty.”
• Fungi and mold spores, which thrive on damp cotton.
• Detergent and fabric softener residue, which never fully rinses out and gives microbes a food source and a place to anchor.
• Body oils, dead skin, and sweat transferred from your body every time you dry off.
• Hard-water minerals (calcium and magnesium) that bind to fibers and detergent, forming deposits that trap odor.

Towels are the perfect host for this. They are thick, absorbent, and spend most of their life damp, which is exactly the environment bacteria and mold need. According to the U.S. Environmental Protection Agency (EPA), mold and microbial growth are driven by moisture, so any fabric that stays wet long enough will start to colonize.

The reason a biofilm survives normal washing is that it is physically protective. Once that matrix forms deep in the loops of a towel, a gentle cold cycle rinses the surface but leaves the anchored layer intact. It rehydrates the moment the towel gets damp again, and the smell returns.

Why Your Towels Smell Musty After Washing

If your towels smell musty right after the machine finishes, or turn sour within a day, the usual culprits are:

Cause	What’s happening	Why it feeds odor
Wash temperature too low	Cold and warm cycles do not reach thermal disinfection range	Bacteria and biofilm survive the wash
Overloaded drum	Towels have no room to agitate and rinse	Residue and microbes stay trapped in fibers
Too much detergent	Excess soap does not rinse away	Leaves a film that feeds bacteria
Fabric softener	Coats fibers with a waxy layer	Seals in oils and blocks water from cleaning
Sitting wet in the machine	Damp towels left in the drum for hours	Bacteria multiply fast in warm, wet fabric
A dirty washing machine	Biofilm builds up in the drum, gasket, and detergent drawer	Re-contaminates every load

That last point matters more than people expect. If the machine itself smells, it is transferring biofilm to clean laundry. Wiping the door gasket, running an empty hot maintenance cycle, and leaving the door open to dry between washes all help. For a broader routine, see our guide on how to sanitize laundry.

How to Get the Musty Smell Out of Towels: The Strip-and-Reset Method

This is a two-wash reset. Do not add vinegar and baking soda to the same cycle. They neutralize each other into mostly salt and water, which cancels the effect you want. Run them separately.

Step 1: Hot Wash With White Vinegar (No Detergent)

1. Load only towels, and do not overfill. Fibers need room to move so water and heat reach every loop.
2. Set the machine to the hottest wash your towels allow, ideally 130°F (54°C) or above. Cotton towels handle high heat well.
3. Add one cup of plain white vinegar to the drum or the fabric softener dispenser. Use no detergent this round.
4. Run the full cycle.

The acetic acid in white vinegar helps dissolve mineral buildup, cut through detergent film, and loosen the biofilm’s grip. Our deep dive on whether vinegar disinfects laundry is worth reading here: vinegar is excellent at stripping residue and deodorizing, but it is not an EPA-registered disinfectant, which is why the heat is doing the real sanitizing work.

Step 2: Hot Wash With Baking Soda or Oxygen Bleach

1. With the same towels still loaded, run a second hot wash.
2. Add half a cup of baking soda directly to the drum. Baking soda is alkaline and neutralizes the acidic odor compounds while gently scrubbing residue.
3. For stubborn or long-neglected towels, swap the baking soda for a scoop of oxygen bleach (sodium percarbonate) instead. Oxygen bleach dissolves in hot water and releases hydrogen peroxide, which the EPA registers as an antimicrobial active ingredient. In a hot laundry cycle it helps lift organic stains and cut odor-causing microbes without the harshness of chlorine bleach, and it is color-safe for most towels.
4. Run the full cycle again.

This second pass finishes what the vinegar started, flushing out the loosened biofilm and neutralizing whatever is left.

Step 3: Dry Fully and Immediately

This step is not optional, and skipping it undoes everything above.

• Move towels to the dryer the moment the wash ends. Do not let them sit damp.
• Dry on high heat until completely, thoroughly dry, not just “mostly.” Any lingering dampness restarts the cycle.
• Line-drying in direct sun is an excellent alternative. Sunlight is widely recognized as having a germicidal effect (the ultraviolet component of sunlight is used as a low-cost water-disinfection method in WHO guidance), and the U.S. Centers for Disease Control and Prevention (CDC) notes that heat and thorough drying help reduce microbial survival on laundry.

The science behind why heat matters is thermal disinfection. The CDC’s guidance on laundry hygiene notes that hot water washing at temperatures around 160°F (71°C) reduces microbial load substantially, and that even where hot water is not used, thorough drying and the chemistry of the wash contribute to hygienic results. Getting the fabric fully hot and fully dry is what actually resets a towel.

How to Keep Towels From Smelling Musty Again

A strip-and-reset fixes the towels you have. Prevention keeps you from doing it every month.

• Do not overload the machine. A drum crammed full cannot rinse properly. Wash towels in smaller batches so they tumble freely.
• Skip the fabric softener. It coats fibers in a waxy film that reduces absorbency and traps odor. If you want softness, add a small splash of white vinegar to the rinse instead, or use wool dryer balls.
• Use less detergent, not more. Excess soap does not rinse clean and becomes microbe food. Follow the dose on the label, and cut it if you have soft water.
• Dry within an hour. Never leave wet towels balled up in the machine or on the floor. If you cannot dry them right away, at least hang them spread out so air can circulate.
• Hang towels to dry flat between uses. A bunched towel on a hook stays damp in the folds. Spread it across a bar so it dries fully before the next use.
• Wash bath towels every three to four uses. Regular laundering prevents biofilm from establishing in the first place.
• Add a periodic sanitizer. Every few weeks, a laundry sanitizer or a hot oxygen-bleach cycle keeps the microbial load low. See our roundup of the best laundry sanitizers for product types that are safe on towels.
• Retire towels that will not reset. Fibers eventually break down and hold residue permanently. If a towel smells sour even after a full strip-and-reset, it has reached the end of its life. Replace it.

Keeping your machine clean is part of prevention, too. A washer with its own biofilm will re-seed every load no matter how carefully you wash.

When “Musty” Might Be Mold

Ordinary sour-towel smell is a hygiene issue, not a health emergency. But if towels are stored in a chronically damp bathroom and you see black or greenish spotting, or the smell is genuinely musty and earthy rather than sour, you may be dealing with mold on the fabric or in the room. The EPA advises addressing the underlying moisture source, because mold will keep returning until the humidity problem is fixed. Improve bathroom ventilation, run an exhaust fan, and store towels somewhere they can dry.

The Bottom Line

Musty and sour towels are caused by biofilm: bacteria (especially Moraxella osloensis), fungi, detergent and softener residue, body oils, and hard-water minerals locked into damp fibers. A gentle cold wash cannot remove it. The fix is a strip-and-reset: a hot vinegar wash, a second hot wash with baking soda or oxygen bleach, and immediate high-heat drying. Then prevent the rebound by not overloading, skipping softener, drying fast, and sanitizing periodically.

For more on washing fabrics hygienically, from sheets to workout gear, visit our laundry hygiene hub.

Frequently asked questions

Why do my towels smell musty even after washing them?

Because a normal wash only cleans the surface. The odor comes from biofilm, a protective layer of bacteria, residue, and oils anchored deep in the fibers. Low wash temperatures, overloading, and fabric softener leave that layer intact, so it reactivates the moment the towel gets damp again. A hot strip-and-reset wash is what removes it.

What bacteria makes towels smell sour?

The sour, damp-laundry odor is widely attributed in laundry science to Moraxella osloensis. This bacterium thrives on the leftover body oils and detergent residue in damp fabric, and as it feeds it releases volatile compounds that produce the distinctive sour smell. Thorough hot washing and full drying are what keep its numbers down.

Can I use vinegar and baking soda together on towels?

No. Adding them to the same cycle makes them neutralize each other into mostly salt and water, canceling the benefit. Run them in separate washes: a hot vinegar wash first to strip residue and minerals, then a second hot wash with baking soda to neutralize odor. Vinegar deodorizes but is not an EPA-registered disinfectant, so the heat does the sanitizing.

What temperature kills the smell in towels?

Heat is the key. The CDC notes that hot water washing around 160°F (71°C) substantially reduces microbial load, and a wash of at least 130°F (54°C) helps strip biofilm from cotton towels. Equally important is drying on high heat or in direct sun immediately after washing, since any lingering dampness lets the odor-causing microbes regrow.

Does fabric softener cause towels to smell?

Yes, indirectly. Fabric softener coats fibers with a waxy film that reduces absorbency and traps body oils and moisture, which feed odor-causing bacteria. It also blocks water from rinsing fibers clean. For softness without buildup, add a splash of white vinegar to the rinse or use wool dryer balls instead of liquid softener.