Your washing machine smells bad — causes and fix
A machine that washes cold and sits damp becomes a breeding ground for mould and bacteria — it's not a fault, it's how every modern washer behaves. The good news: almost all of that smell clears with a cheap home clean, no technician and no expensive products needed. Work through these steps in order.
The problem
When you open the door you get a musty, damp smell — that 'old socks' odour — and sometimes the laundry itself comes out smelling less than fresh even after a wash. In other cases the smell is more like sewage or rotten eggs, and that's different: it comes from the drain, not from built-up grime.
Likely causes
Mould and bacteria (biofilm) in the door seal and drawer (the number one cause)
Front-loaders have a rubber gasket around the door, and inside its folds water, hair, lint and detergent residue get trapped — food, water and warmth, a perfect home for black mould. The same happens in the detergent drawer. This slimy biofilm is the main source of the musty smell, and it only comes off with hand-scrubbing — a hot wash alone won't shift it.
Standing water in the drum, sump or drain hose
If your machine leaves water sitting in the bottom after each wash, or the drain hose has a loop that traps water, that stagnant water goes stale and starts to smell. Front-loaders in particular keep a little water in the sump (the pump housing) by design — but once it builds up and sits, it stinks.
Too much detergent and softener
The single most common mistake is using far more than you need. The excess doesn't all rinse away, so soap scum and sticky softener residue build up in the drawer, seal and drum — and that residue is ready-made food for bacteria. Softener especially is sticky and nests everywhere. Less detergent means less foam, less residue and less smell, not more.
A clogged pump (lint) filter
Most front-loaders have a small filter behind a flap low on the front that catches coins, pins, hair and tissue. Once it saturates and turns foul it becomes a strong smell source on its own, and it also slows draining, so standing water gets worse. Plenty of people have never once opened this filter — and it holds surprises.
Shutting the door and drawer after every wash
If you close the door and drawer while the machine is still damp inside, it never dries and stays sealed with trapped moisture for 24 hours — which is exactly what grows the mould. One simple habit: leave the door and drawer ajar between washes. It makes a big difference.
A sewage smell = a drain problem, not the washer
If the smell is sewage or sulphur (rotten eggs) rather than musty, the cause is usually not inside the machine at all. Either the drain trap that blocks sewer gas has dried out or is missing, or the drain-hose connection at the wall isn't sealed, so sewer gas escapes there. That's a plumbing job, and it's fixed at the drain.
Fix it — step by step
- Run a hot, empty maintenance washWith no laundry, add one cup of citric acid (or two cups of white vinegar) to the drum plus half a cup of baking soda, and run the longest programme at the hottest temperature you have (90°C if available, or a dedicated 'tub clean' cycle if your machine has one). This dissolves scale and kills most of the bacteria.Don't mix the vinegar and baking soda together in one spot at the same instant — put the acid/vinegar in the drum and the baking soda in the drawer so they act across the cycle instead of cancelling out immediately.
- Scrub the rubber door seal and its foldsOnce the machine has cooled, gently peel back the fold of the rubber gasket around the door — you'll find black water, hair, lint and grime collected inside. Wipe it all out with a cloth soaked in vinegar or cleaning solution, and scrub the corners with an old toothbrush.Look for any small object trapped in the fold (pins, coins, buttons) — very often it's the thing seeding the main patch of mould.
- Pull out the detergent drawer and clean itMost drawers come out fully by pressing a release tab in the middle. Take it out, soak it in hot water, and scrub every corner — especially the softener compartment, which is usually caked in a sticky blue/white layer. Also brush out the cavity the drawer sits in.If the sticky layer is stubborn, soak the drawer in hot vinegar for fifteen minutes before scrubbing — it loosens on its own.
- Open and clean the pump (lint) filterUnplug the machine. Open the small flap low on the front. Put a towel and a shallow tray underneath because water will come out, then unscrew the filter cap slowly to release the water in stages. Take the filter out, clear the lint, hair and coins, rinse it and refit it tight.If no water comes out at all when you open it, the drain is blocked before the filter — check the drain hose. And if the filter was truly foul, that alone was half your problem.
- Dry everything and leave the door and drawer ajarWipe the door seal, glass and drum with a clean dry cloth until they're dry. From now on, always leave the door and drawer slightly open between washes so moisture escapes and mould can't take hold again.If the machine is in a closed space (a small bathroom or a cupboard), open a window or run an extractor fan after washing — trapped humidity is the enemy.
- Use less detergent and a hot wash now and thenGoing forward, use half the detergent you were using, and cut the softener or replace it with white vinegar in the softener compartment (it softens and leaves no residue). And once a month, run an empty hot maintenance wash so the smell can't return.Always washing cold lets mould build up over time — a monthly hot wash resets the count.
Tools & parts you'll need
When to call a professional
The whole clean is safe home work — but two situations need someone else: (1) if the smell is sewage-like and it lingers after you've cleaned the seal, drawer and filter, the problem is in the drain (a dried-out trap, a loose hose connection, or sewer gas backing up) and that's a plumber's job. (2) if the machine won't drain properly and leaves standing water even after you've cleaned the pump filter, the pump itself may be weak or failed, or the drain hose is blocked internally — and that needs an appliance technician.
If you'd rather bring in a professional, look for a trusted local technician — and the other Osta guides list vetted technicians by country.
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How often should I clean my washer to keep smells away?
An empty hot maintenance wash once a month is enough for most homes. Wipe the door seal fold with a cloth after roughly every wash (two seconds that saves you from mould), and clean the pump filter every 2-3 months. If you always wash cold, bump the hot wash up to twice a month.
Vinegar or bleach to clean it?
Vinegar and citric acid are better and safer for routine use — they dissolve residue and don't harm the rubber. Bleach kills mould but hardens the rubber seal over time and gives off fumes, and you must never mix it with vinegar (that makes a toxic gas). For very stubborn black mould, use diluted bleach once, then go back to vinegar for the routine.
What's the difference between a musty smell and a sewage smell?
A musty/damp smell (like socks or a cellar) comes from mould and residue inside the machine — it's fixed by the clean above. A sewage or sulphur (rotten-egg) smell comes from the drain: a dried-out trap letting sewer gas back up, or a loose hose connection. That won't clear by cleaning the washer — you have to treat the drain.
Mine is a top-loader — is the fix the same?
Mostly yes: empty hot wash, clean the drawer, use less detergent. The difference is that top-loaders don't have a rubber door gasket for mould to hide in, so they usually smell less — but they do have an inner tub that can build up residue, and they rarely have the front pump filter that front-loaders do.
The laundry comes out smelling off even after washing — why?
Because the machine itself is foul, so it's contaminating the laundry instead of cleaning it. Clean the washer with the steps above, cut the detergent, and use a hot wash. And don't leave wet laundry sitting inside after the cycle finishes — take it out and hang it straight away, because leaving it for hours is a big cause of the smell.