The One-Second Habit That Could Save Your Washing Machine from Mould – And You from Health Risks

According to HONEY

A Cry for Help from a New Renter

When one renter opened the washing machine in their new apartment, they were greeted not by the smell of detergent, but by the musty, sour scent of mould. The appliance, a front-loading washer, had clearly been neglected by previous tenants—its door seal blackened, the drum tinged with decay.

The tenant turned to Reddit for advice, sharing photos and detailing how “countless tub cleans” and scrubbing still couldn’t remove the stubborn mould lodged within the machine’s seal.

It was a domestic horror story shared by many. And in doing so, it revealed a remarkably common oversight in household hygiene: not leaving the washer door open after use.

The Real Problem Lurking in the Seal

At the heart of the issue lies a small but critical component—the rubber door gasket, or seal. Designed to keep water in during washing cycles, this flexible ring can also trap moisture and detergent residue.

Over time, this becomes a perfect breeding ground for mould, particularly Stachybotrys chartarum, a toxic black mould known for thriving in damp environments.

This fungus isn’t just an eyesore. Its spores can trigger allergies, respiratory irritation, and—in prolonged exposure—more serious health risks for vulnerable individuals, especially in poorly ventilated homes.

A Simple Step Many Never Knew

Surprisingly, much of this can be avoided with a one-second habit: leaving the washing machine door ajar after each use.

Many commenters on Reddit confessed they had never heard of this tip. “BRB, opening my washer door real quick,” one wrote. Another added, “Why would you leave the washer door open? Who else does this?”

While it might seem counterintuitive—leaving an appliance open—it’s one of the most effective methods to allow airflow, prevent moisture buildup, and stop mould before it starts.

The Ripple Effects of a Mouldy Washer

It’s not just the machine that suffers. Washing clothes in a mould-infested washer means:

• Clothes may come out smelling musty, no matter how much detergent is used
• Spores may cling to fabrics, posing a risk to those with asthma or allergies
• Detergent efficacy drops, as mould can interfere with water quality and temperature regulation

The renter in question had scrubbed, soaked, and sanitized with little success. Eventually, they decided to try a mould remover gel while awaiting a landlord response. Meanwhile, the community flooded them with solutions—some DIY, others suggesting total gasket replacement.

Landlord or Tenant Responsibility?

The issue also raises questions of responsibility. Several commenters insisted the property manager should replace the appliance or at least the gasket. One Redditor shared, “I had a similar situation when I moved in, and they replaced mine with a brand new one.”

In many regions, if a landlord provides a washing machine as part of the tenancy, they’re required to ensure it’s safe and hygienic to use. Tenants are encouraged to report such issues formally, backed with photos, and avoid making expensive repairs unless authorized.

How to Clean a Mouldy Washer (When You’re on Your Own)

If a professional fix isn’t forthcoming, there are still effective home remedies:

Step-by-step cleaning tips:

• Run an empty hot cycle with bleach or a washing machine cleaner
• Soak the gasket with paper towels soaked in white vinegar or bleach, leaving them in place for 1–2 hours
• Use a soft brush (or old toothbrush) to scrub inside the folds of the seal
• Remove and dry the detergent drawer after each wash
• Wipe down all surfaces after use, especially around the door and glass

Some also recommend natural mould-killing solutions like tea tree oil mixed with water or hydrogen peroxide sprays.

Front Loaders vs. Top Loaders: Who’s More at Risk?

Front-loading washers are more efficient and use less water, but they come with a downside: they’re more susceptible to mould. Their airtight door seals and horizontal drum position encourage moisture retention—unless proper airflow is maintained.

Top loaders are less prone, but not immune. Mould can still develop in detergent drawers, filters, and lint traps. The key difference? Top loaders often allow more airflow simply due to their lid shape and vertical design.

But no matter the model, routine care is the real defence.

The Forgotten Zone: Detergent Dispensers and Filters

Aside from the drum and door, mould can hide in the washing machine’s detergent dispenser drawer and lint filters. These components retain water after every wash, especially if overfilled or not drained properly.

• For front loaders, filters are often located at the bottom front corner. Empty and clean monthly.
• For top loaders, lint filters inside the drum should be cleared after every wash.
• The detergent drawer should be removed and dried, and occasionally soaked to remove soap scum buildup.

Ignoring these spots invites mould to spread silently, unseen until it starts to smell—or worse.

Mould: A Health Hazard, Not Just a Nuisance

While often dismissed as “just a cleaning issue,” black mould is medically recognized as a health hazard. Stachybotrys chartarum releases spores that can lead to:

• Coughing or sneezing
• Skin irritation
• Eye discomfort
• Asthma attacks
• Chronic sinus issues

For households with infants, elderly family members, or immunocompromised individuals, the presence of mould isn’t minor—it’s urgent.

Preventative Care: The One-Minute Maintenance Routine

To protect your machine—and your health—adopt this after-wash ritual:

Leave the door and detergent drawer open
Wipe the seal and drum dry with a towel
Empty lint and water filters
Run a hot, empty cycle with vinegar or machine cleaner once a month
Use only the recommended amount of detergent—excess leads to residue, which feeds mould

These steps, all together, take less than a minute but offer long-term protection against costly repairs, unsanitary clothes, and potential illness.

A Teachable Moment for Millions

This Reddit thread, while sparked by one renter’s frustration, became an unlikely classroom for thousands. It revealed how little many people know about appliance care—and how even simple lapses can lead to uncomfortable, unsanitary situations.

Like flossing or airing out your bathroom, keeping your washer dry is one of those small, unglamorous habits that pay dividends in health, savings, and peace of mind.

A Door Left Open Can Close the Door on Mould

The next time you finish a load of laundry, resist the urge to slam the washer shut and move on. Instead, take a breath. Leave the door open.

That simple act could keep your clothes cleaner, your lungs healthier, and your landlord from receiving another maintenance request.

Because sometimes, the best defence against mould is just a little fresh air.

References

• CDC – Mould and Health
• WHO – Asthma Fact Sheet

According to HONEY

Frequently Asked Questions

Why do front-loading washing machines get mould so easily?

Front-loading (horizontal axis) washing machines have several design characteristics that create excellent mould growth conditions that top-loading machines largely avoid. The door gasket: front-loaders have a large, complex rubber door gasket (the seal that prevents water from escaping through the door opening) with multiple folds and ridges; after each cycle, water residue and fine fabric debris collect in the folds of this gasket; when the door is closed, this area becomes a warm, dark, persistently damp enclosure—ideal for mould colonisation. The sealed drum: the drum of a front-loader, when the door is closed, creates a nearly sealed enclosure; warm humid air within the drum after washing cannot escape and condenses on drum surfaces as they cool, maintaining surface moisture. Detergent accumulation: the baffles (the paddles inside the drum that agitate clothes) and the recessed areas around the drum rim collect soap residue and debris that, combined with moisture, provides a nutrient-rich mould substrate. Drainage design: the gasket drain channel at the bottom of the door opening can trap water if not adequately draining. Top-loading machines: the open top design allows the drum interior to air-dry naturally between uses; they do not have the front door gasket; the vertical drum orientation allows gravity-draining that reduces residual moisture.

What is the best way to prevent mould in a washing machine?

Preventing mould in a front-loading washing machine requires systematic maintenance across all the mould-prone components, not just the door gasket. After every cycle: leave the door fully open or at least ajar for at least 1–2 hours after the last cycle (or permanently when the machine is not in use); wipe the door gasket folds with a dry cloth to remove trapped water and debris; pull out and drain the detergent dispenser if it contains residual water. Weekly: wipe the door gasket thoroughly including inside all the folds with a clean, dry cloth; check the gasket drain hole (usually at the bottom of the gasket) for debris blockage and clear if needed. Monthly: run a drum-cleaning cycle at high temperature (60–90°C) with a washing machine cleaning tablet or 250ml white vinegar in the drum (no clothes); clean the detergent dispenser by removing it and washing in warm soapy water; check and clean the pump filter (usually accessed through a panel at the bottom front of the machine)—a blocked filter causes poor drainage and increased residual water. Every 3–6 months: check the drum baffles for residue accumulation; clean with a damp cloth and mild detergent if needed. Detergent management: use only HE-rated low-suds detergent in the correct quantity (overusing detergent is one of the most common causes of residue build-up); avoid fabric softener which leaves a coating on drum surfaces that feeds mould.

Is the mould in my washing machine dangerous to health?

Washing machine mould poses a health risk that is real but often modest for healthy adults—though it is more significant for sensitive individuals and in heavily contaminated machines. Health risk assessment: the mould species most commonly found in washing machines (Aspergillus, Cladosporium, Penicillium) are common environmental fungi that healthy immune systems typically manage without illness. The primary health concern is allergic sensitisation and exacerbation—repeated exposure to mould spores can sensitise susceptible individuals, and subsequent exposures then trigger allergic symptoms (rhinitis, asthma, eczema). For individuals already sensitised to mould, living with a heavily contaminated washing machine increases their mould exposure burden and may worsen allergic symptoms. The ‘laundering risk’: clothing washed in a mould-contaminated machine carries mould residue; items like bedding, towels, and underwear dried against contaminated fabric are a potential sensitisation pathway. Immunocompromised individuals (chemotherapy, transplant recipients, HIV with low CD4 counts) are at risk of invasive infection from Aspergillus and other moulds; running laundry in a heavily mould-contaminated machine that distributes spores throughout the home is a meaningful risk factor in these circumstances. Prompt action: if washing machine mould is suspected, thorough cleaning and remediation (as described above) should be completed before the machine continues to run.

How often should you run a cleaning cycle on your washing machine?

Washing machine cleaning cycle frequency recommendations from manufacturers, appliance professionals, and cleaning experts have converged on monthly as the minimum appropriate frequency for machines in regular household use. Evidence for monthly cleaning: drum biofilm (the thin layer of bacteria, mould, and organic material on drum surfaces) accumulates through normal washing use; monthly high-temperature cleaning cycles with a drum-cleaning product substantially reduce biofilm levels and visible mould development in research comparisons of different cleaning frequencies. Manufacturer guidance: most major washing machine manufacturers (Miele, Bosch, LG, Samsung, Whirlpool) recommend monthly drum cleaning cycles in their owner manuals. Frequency adjustments: increase cleaning frequency if: the household washes large volumes (5+ loads per week); the machine is used predominantly for cold-water cycles (which are energy-efficient but less effective at killing accumulated microorganisms); there is visible or odour-evident mould present (requiring more frequent cleaning until the problem is resolved); household members are immunocompromised. What effective drum cleaning requires: a true ‘drum clean’ requires high temperature (60°C minimum, 90°C preferred) for at least 30 minutes; many machines have a specific ‘drum clean’ cycle; alternatively, use the highest-temperature hot-wash setting. Using a proprietary drum cleaning tablet (e.g., Dettol, Calgon, Affresh) or 250ml of white vinegar as the ‘detergent’ provides antimicrobial activity beyond what hot water alone achieves.

Can mould from a washing machine make clothes smell musty?

Yes—washing machine mould is one of the most common causes of musty-smelling laundry, and it is a frustrating problem where clothes smell fine immediately after washing but develop a mouldy odour within hours of drying, or smell musty as soon as the machine door is opened. The mechanism: mould colonies in the door gasket, drum surfaces, and detergent dispenser produce MVOCs (microbial volatile organic compounds) that are absorbed by fabrics during washing; these MVOCs have characteristic musty, earthy odours; heat from drying can volatilise them, causing musty odour during or after drying. Secondary mould contamination: in heavily contaminated machines, mould spores and hyphae transfer to fabrics during washing; if fabrics are not dried rapidly and completely (particularly thick items like towels and jeans), the residual mould from the machine can grow on slightly damp fabric during slow drying, producing additional musty odour independent of MVOCs. Solving the problem: clean the washing machine thoroughly as described above (including gasket, drum, and detergent dispenser); run a complete cleaning cycle before attempting to solve the laundry odour problem (clothes washed in a contaminated machine will continue to smell musty regardless of detergent used); wash musty fabrics again after machine cleaning using a hot wash cycle with an odour-neutralising additive (white vinegar, baking soda, or a commercial laundry sanitiser); dry fabrics quickly and completely (tumble drying or rapid outdoor air drying).