Section
Quick Fix Summary
- Main cause: Mold and biofilm in the door gasket and inner drum
- Cure: Hot cycle with vinegar + scrub the gasket + clean dispenser + clean pump filter
- Prevention: Leave door open, promptly remove wet clothes, monthly drum clean
- Front-load: Much more prone to odour than top-load — gasket is the #1 source
A washing machine that smells musty, mildew-like, or like a wet dog is one of the most common appliance complaints — and it is entirely fixable. The smell comes from mold, mildew, and bacteria that grow inside the machine, and the fix is a thorough cleaning followed by better usage habits that prevent the smell from coming back.
This guide explains exactly why washing machines develop odours, how the cleaning process differs between front-load and top-load machines, and the prevention habits that make the difference between a one-time fix and a permanent solution.
Why Do Washing Machines Smell?
The odour is caused by mold, mildew, and bacteria growing inside the machine. These microorganisms thrive in a washing machine because it provides exactly what they need: moisture, warmth, darkness, and a food source (detergent residue, fabric softener, and skin cells from clothing).
The smell is amplified by a few common habits:
- Always washing in cold water — cold cycles do not kill bacteria or dissolve soap scum effectively. Using mostly cold cycles allows biofilm to build up inside the drum and hoses over time.
- Using too much detergent — excess detergent does not fully rinse away, leaving a residue that bacteria and mold feed on.
- Leaving the door closed — traps moisture inside, preventing the drum and gasket from drying between washes.
- Leaving wet clothes in the drum — even for a few hours, this creates ideal mold-growing conditions inside the machine.
Front-Load vs. Top-Load — Why Front-Load Smells Worse
Front-Load Washers
- Deep rubber gasket creates a sealed, moisture-trapping environment
- Gasket folds collect lint, hair, and soap residue
- Door creates an airtight seal — drum does not air out
- Higher efficiency means less water to flush out residue
- More prone to severe odour problems
Top-Load Washers
- No sealed door gasket — drum is open to air from above
- Drum dries out naturally between washes
- Larger water volumes rinse soap more effectively
- Still susceptible to odour in the dispenser and agitator base
- Less severe odour problems overall
Step-by-Step: Cleaning a Smelly Washing Machine
Run a Hot Cycle with White Vinegar
Pour 500 ml of white distilled vinegar directly into the drum (not the dispenser). Set the machine to the hottest available wash cycle and run it empty. The hot water combined with vinegar breaks down soap scum, biofilm, and mineral deposits from the drum walls and internal components. Vinegar is acidic and effective against the bacteria and mold that cause odour.
Run a Second Cycle with Baking Soda
After the vinegar cycle finishes, add 125 g (about half a cup) of baking soda directly to the drum. Run another hot empty cycle. Baking soda is alkaline and deodorizing — it neutralizes remaining acids and any residual odour compounds that the vinegar loosened but did not fully remove. Together, the vinegar and baking soda cycles are highly effective at eliminating established odours.
Scrub the Door Gasket (Front-Load)
This is the most important manual step for front-load machines. Open the door and fold back the rubber gasket to expose the inner folds. You will likely find a dark, slimy buildup — this is mold. Mix a solution of equal parts white vinegar and water, dip a cloth or soft-bristled toothbrush into it, and scrub all surfaces of the gasket — inside every fold, around the entire circumference, and especially the bottom trough where moisture pools. For stubborn black mold spots, see our dedicated mold removal guide.
Clean the Dispenser Drawer
Remove the dispenser drawer fully (most pull out with a press-and-lift on the release tab in the softener compartment). Rinse all compartments under warm water and scrub with a toothbrush to remove hardened detergent and fabric softener buildup. Wipe the dispenser housing inside the machine — mold thrives on the wet surfaces of the housing walls. Dry and reinsert the drawer.
Clean the Pump Filter
On front-load washers, the pump filter at the bottom front of the machine traps lint, hair, and debris. A dirty, clogged filter is itself a source of bad smells — it is a pool of stagnant water and decomposing organic material. Clean it every 3 months, or now as part of this deep clean. Drain the filter access, unscrew the cap, rinse the filter, and reassemble.
Do not mix vinegar and bleach in the same cleaning cycle. White vinegar (acetic acid) and bleach (sodium hypochlorite) react to produce chlorine gas, which is toxic. If you want to use bleach instead of vinegar for a particularly severe mold situation, use bleach in its own separate cycle, then run an extra rinse cycle before using the machine for laundry.
Prevention: How to Keep the Smell from Coming Back
Cleaning cures the problem — prevention keeps it from returning. These habits make a dramatic difference:
- Always leave the door ajar after the last wash of the day. This is the single most effective prevention step for front-load washers. Airflow through the drum and gasket allows moisture to evaporate, denying mold the conditions it needs to grow.
- Pull the dispenser drawer out slightly. Same principle — allows the dispenser housing to dry out between washes.
- Remove wet laundry immediately. Even 1–2 hours of wet clothes sitting in a sealed drum creates mold-growing conditions. Transfer to the dryer or drying rack right after the cycle ends.
- Run a hot wash weekly. Even if most of your laundry is cold, run at least one hot cycle per week — bed sheets, towels, or whites. The heat kills bacteria and prevents biofilm from establishing.
- Use HE detergent and the correct amount. HE machines (all front-loaders) require HE-specific low-sudsing detergent in the measured amount — not more. Excess detergent or regular detergent in an HE machine creates the soap scum residue that feeds odour-causing bacteria.
- Monthly drum clean cycle. Run the machine's drum clean or Self Clean cycle once a month with an empty drum — no additional products needed if done consistently.
Frequently Asked Questions
When an appliance is not working in the Greater Toronto Area, the usual culprits are a worn part, a failed motor or pump, a faulty sensor or control board, or normal wear after years of use. Our technician pinpoints the exact cause during the $89 diagnostic and gives you a clear repair quote — most appliance repairs are finished the same day.
Yes. Nick's offers same-day appliance repair across the Greater Toronto Area and the wider GTA, Monday to Saturday 8am–8pm and Sunday 9am–6pm, with no travel surcharge.
As a rule of thumb, repair is worth it when the fix costs less than half the price of a comparable new appliance. Our technician gives you an honest recommendation during the diagnostic so you can decide with no pressure.
In most cases we can book your appliance repair the same day or the next day in the Greater Toronto Area, and the majority of repairs are completed in that single visit.
The musty smell comes from mold and mildew growing inside the washer — primarily in the door gasket (front-load models), inside the drum, and in the detergent dispenser. The conditions that cause it: cool, dark, moist environment with soap residue for bacteria to feed on. Using cold water cycles and leaving the door closed between washes accelerates the problem.
White distilled vinegar used monthly in a cleaning cycle is safe for most washing machines. However, frequent use of vinegar can over time degrade rubber gaskets and seals on some machines. Use it for periodic deep cleaning — once a month at most — and not as a regular laundry additive.
Front-load washers have a thick rubber door gasket that creates a water-tight seal — excellent for efficiency but terrible for drying out between washes. The gasket traps moisture, lint, and soap residue in its folds, creating the ideal environment for mold. Top-load washers have no sealed gasket and the drum is exposed to air from above, so they dry out between washes much more readily.
Yes — a diluted bleach cycle is effective for killing mold inside the drum and on the gasket. Add 250ml of liquid chlorine bleach to the drum (not the dispenser), run the hottest available empty cycle. Do not mix bleach with vinegar in the same cycle — the combination produces chlorine gas. Run a rinse cycle after to clear bleach residue.
Three habits prevent the smell from returning: (1) leave the door ajar and dispenser drawer open after every wash, (2) remove wet laundry from the drum promptly — never leave wet clothes sitting for hours, (3) run a hot wash or drum clean cycle monthly. Using HE detergent in the correct amount also reduces soap buildup significantly.
Clothes that smell musty or mildew-like after washing usually indicate mold inside the washing machine contaminating clean laundry. This is most common with front-load washers with neglected gaskets. Clean the machine thoroughly using this guide, then rewash the affected laundry with a hot cycle.
No — a smelly washing machine will only get worse over time without intervention. Mold colonies in the gasket and drum continue to grow with each wash cycle. A thorough cleaning routine eliminates the odour within one to two cleaning sessions for most machines.