Musty washing machine smell: how to clean your machine properly
By the Pacco Pacco Laundry team · Updated 18 September 2026 · 4 min read
The short answer
A musty washing machine means biofilm: a layer of bacteria, mould, detergent residue and lint coating the drum, seal and pipes, fed by cold washes and a door kept closed between loads. Fix it with an empty maximum-heat wash using washing machine cleaner, oxygen bleach or two cups of white vinegar, plus a hand-clean of the door seal, detergent drawer and lint filter. Keep it away by leaving the door and drawer ajar between washes, dosing detergent correctly and running a hot wash monthly.
Why does a machine that cleans things start to stink?
Modern habits are the culprit: cold washes and concentrated liquid detergents are great for clothes and power bills, but they never get the machine itself hot enough to self-clean. Residue from detergent and fabric softener builds into a film on every wet surface, and bacteria and mould move in. Front loaders are especially prone because the rubber door seal traps a puddle, and a closed door keeps everything humid between loads.
The smell transfers, too. If clean towels come out smelling sour before they've even been used, the machine is usually the source, not the towels.
The monthly service wash
Run the machine empty on its hottest cycle, 60–90°C, using either a commercial washing machine cleaner, a scoop of oxygen bleach, or two cups of white vinegar in the drum. Many machines have a dedicated drum-clean cycle; use it if you have it. This dissolves the film that daily cold washes leave behind.
Once a month is the rhythm that keeps smells from returning. If it's been years, do two back-to-back service washes and expect the first to rinse out some unpleasant debris; that's the build-up leaving.
The three spots the hot wash can't reach
The service wash handles the drum, but the smelliest zones need hands.
- Door seal: peel back the rubber folds on a front loader and wipe out the trapped water, lint, hair and the black mould that loves it, using warm soapy water or diluted vinegar. Stubborn black staining in the rubber is mould that has penetrated; it can be cleaned back but heavy staining may need the seal replaced
- Detergent drawer: pull it out completely (most have a release tab), scrub off the caked residue and any mould at the back of the cavity, dry it and refit
- Lint filter: usually behind a flap at the bottom front on front loaders, in the agitator or drum lip on top loaders. Put a towel down, drain, and clear the coins, hair ties and sludge. Check it every month or two
Habits that keep it fresh
Leave the door and detergent drawer open between washes so the machine dries out; this one habit prevents most odour. Don't overdose detergent, go easy on fabric softener or drop it entirely, get finished loads out promptly rather than leaving them to sit wet, and let the monthly hot wash do its job.
A clean machine also washes better: the same residue that smells is what greys whites and leaves towels sour. If a backlog of washing built up while the machine was out of favour, a Pacco Pacco pickup can clear the mountain in one 48-hour round trip while you get the machine back in shape.
Quick questions
Vinegar or bleach for cleaning a washing machine?
Either works: vinegar or oxygen bleach in an empty hot wash are the gentle standbys, and purpose-made machine cleaners are effective too. Don't combine chlorine bleach and vinegar in any cleaning job; the mixture releases toxic gas.
How often should I clean the washing machine?
An empty hot service wash monthly, the door seal and drawer wiped at the same time, and the lint filter checked every month or two. More often if you wash mostly cold or the machine lives in a humid laundry.
Why do my clothes smell worse after washing?
Almost always a machine problem: biofilm re-contaminating each load, or loads left sitting wet in the drum. Do a service wash, clean the seal and filter, and get washing out promptly, and the problem usually disappears.