How To Get Sour Smell Out Of Towels and Stop It From Coming Back

A towel that smells sour right after washing is one of the more frustrating laundry problems to fix. The smell returns quickly, even when the towel looks clean. Knowing how to get sour smell out of towels means addressing the actual cause rather than masking it with more detergent or fragrance.

The source of the smell is bacterial. Research published in Applied and Environmental Microbiology via NCBI identified Moraxella osloensis as the bacterium primarily responsible for the sour, musty odor in laundered textiles. This gram-negative bacterium lives on human skin and transfers to towel fibers during use. It produces a compound called 4-methyl-3-hexenoic acid, which creates the distinctive wet cloth smell. The same research notes that this bacterium is resistant to UV light, drying, and some antimicrobial detergents, which explains why standard washing often fails to fully eliminate the odor. A 2024 study in MicrobiologyOpen via NCBI confirmed that Moraxella osloensis resists not just UV and drying but also quaternary ammonium-based antimicrobial detergents commonly used in laundry products.

Why Towels Develop a Sour Smell

Sour-smelling towels are not a sign of poor hygiene. They are a sign that specific conditions in the laundry routine allow bacterial growth to persist inside the fibers. Once that pattern takes hold, it repeats with every wash cycle.

Several factors contribute to the problem:

• Staying damp too long: Towels that do not dry fully give bacteria the moisture they need to multiply. Terry towel loops hold moisture deep inside the fiber long after the outer surface feels dry.

• Too much detergent: Excess detergent leaves residue inside the fibers that traps moisture and body oils, which feed bacterial growth between washes.

• Fabric softener use: Fabric softener coats fibers with a waxy layer that reduces absorbency and gives bacteria more surface area to colonize over time.

• Washing in cold water: Cold water cleans surface dirt but does not kill bacteria embedded in towel fibers. Moraxella osloensis survives cold wash cycles regularly.

• A dirty washing machine: Front-loading machines collect residue in door seals and detergent drawers. That residue transfers directly to towels during the wash, reintroducing bacteria even after the cycle ends.

How To Get Sour Smell Out Of Towels: The Vinegar and Baking Soda Method

The most effective method for how to get sour smell out of towels uses two wash cycles back to back. Vinegar breaks down bacterial residue and mineral deposits. Baking soda neutralizes the odor compounds that remain after the vinegar cycle.

Here is the full process:

1. Place the sour-smelling towels in the washing machine. Do not add detergent.

2. Add one cup of white distilled vinegar directly to the drum or the detergent tray.

3. Run a full wash cycle on the hottest water setting the towel care label allows.

4. Without removing the towels, run a second full wash cycle. This time, add half a cup of baking soda to the drum. Skip the detergent again.

5. Transfer towels immediately to the dryer or an outdoor line after the second cycle. Do not leave them sitting in the drum.

6. Dry on low to medium heat until completely dry, including the center layers.

Do not mix vinegar and baking soda in the same cycle. They cancel each other out when combined in water. Running them separately lets each one do its job fully. After this two-cycle treatment, the sour smell is typically gone entirely, not just reduced.

How To Get Sour Smell Out Of Towels When the Smell Persists

If the vinegar and baking soda method does not fully clear the odor, the towel likely has a deeper biofilm buildup that requires stripping. Towel stripping pulls out the layers of detergent residue, fabric softener, minerals, and bacteria that regular washing cannot reach.

The Stripping Method

Stripping works best in a bathtub or large bin rather than a washing machine. The extended soak time is what makes it effective.

Follow these steps:

1. Fill the bathtub with very hot water, around 140°F (60°C) if possible.

2. Add one quarter cup of borax, one quarter cup of washing soda, and half a cup of powdered laundry detergent. Stir until fully dissolved.

3. Submerge the towels and press them down so all fibers are soaked.

4. Let them soak for two to four hours, stirring every 30 minutes.

5. Drain the tub and wring out excess water.

6. Transfer to the washing machine and run a full rinse cycle with no detergent.

7. Dry completely on low heat or air dry in a well-ventilated space.

The water will turn brown or gray during the soak. This is normal. It shows the process is drawing out what regular washing left behind. For a full breakdown of the stripping process and when to use it, the how to strip towels guide covers each step in detail.

Washing Machine Maintenance and Sour Towel Smell

A sour smell that returns immediately after washing often points to the washing machine rather than the towels. Front-loading machines are especially prone to mold and bacteria growth in the rubber door seal and detergent drawer. Every load that runs through a contaminated machine picks up bacteria before the cycle even finishes.

To clean a front-loading machine:

• Run a hot empty cycle with two cups of white vinegar and half a cup of baking soda added to the drum.

• Wipe the rubber door seal after every use. Mold accumulates fastest in the folds where water pools.

• Leave the machine door open between uses so the drum dries fully.

• Clean the detergent drawer monthly by removing it and soaking in warm water before scrubbing off residue.

Running a machine cleaning cycle monthly prevents bacterial recontamination of towels during the wash.

How To Prevent Sour Smell in Towels Going Forward

Removing the odor is only part of the fix. Preventing it from returning requires changes to both the laundry routine and how towels are stored between uses.

A 2023 study published in Scientific Reports via PubMed found that biofilm structures and bacterial counts in towels increased steadily over time with daily use. Odor and dullness appeared after just two months. The key finding is that bacterial colonization is cumulative. Each use and hang cycle adds to the load inside the fibers unless the drying conditions actively work against bacterial growth.

Here are habits that stop sour smell from returning:

• Dry towels fully after every use. Hang them spread flat across a wide bar. Folded or bunched towels keep moisture trapped inside for hours. The how to hang towels in bathroom guide covers placement and technique for faster drying between uses.

• Wash every three to four uses. Letting towels go longer increases the bacterial load beyond what a single wash can clear.

• Use less detergent. Half the recommended amount leaves fewer residue deposits for bacteria to feed on.

• Skip fabric softener entirely. Replace it with half a cup of white vinegar in the rinse cycle. Vinegar softens fibers and leaves no residue.

• Dry on low heat fully. Confirm the center of the towel is completely dry before folding. A towel stored with residual moisture will smell sour within hours.

Choosing Towels That Resist Sour Smell

Towel construction affects how quickly odor builds up. Terry towels with thick, tightly packed loops hold moisture longer and give bacteria more surface area to colonize. Waffle weave towels have an open grid structure that dries faster and gives bacteria less time to establish between uses.

Long-staple cotton like Supima holds up better through repeated hot washing than standard cotton, so towels can be laundered at higher temperatures without losing softness. The Supima waffle towels from Onsen combine a faster-drying weave with high-quality fiber that stays fresher between washes.

Knowing how to get sour smell out of towels comes down to treating the bacteria causing the odor rather than masking it. The vinegar and baking soda method handles most cases. Stripping handles persistent buildup. And consistent drying habits keep the smell from returning between washes.

Sources:

Complete Genome Sequence of Moraxella osloensis Strain KMC41, a Producer of 4-Methyl-3-Hexenoic Acid, a Major Malodor Compound in Laundry

Analysis of Biofilm and Bacterial Communities in the Towel Environment With Daily Use

Bacillus xiamenensis Inhibits the Growth of Moraxella osloensis by Producing Indole-3-Carboxaldehyde