Short answer
Run a maintenance wash at 60 °C or hotter once a month, wipe the door seal dry after every load, and clean the lint filter every three months. If you wash mostly at 30 °C, shorten the maintenance wash to every three or four weeks.
The intervals at a glance
| Task | Interval | Why |
|---|---|---|
| Maintenance wash at 60–90 °C | monthly | Dissolves detergent residue and biofilm in drum and pipes |
| Wipe the door seal | after every load | Standing water in the fold is the most common source of mould |
| Rinse the detergent drawer | monthly | Softener residue cakes in the chamber and grows mould |
| Empty the lint filter | every 3 months | Otherwise it eventually blocks the drain pump |
| Check the inlet filter | yearly | Limescale and grit choke the water intake |
Why a machine that washes still needs washing
A washing machine runs on water and detergent, so it is easy to assume it cleans itself along the way. The opposite is true. For energy reasons modern cycles run at 30 or 40 °C, and that range is close to ideal for bacteria and yeasts. Together with detergent residue and textile fibres they settle as a greasy biofilm: on the back of the drum, in the drain hose and above all in the fold of the door seal.
The first sign is smell — freshly washed laundry comes out musty even though it is clean. By then the biofilm is well established. A maintenance wash before it smells is far less work than remediation afterwards.
The monthly maintenance wash
Once a month the machine runs empty at 60 °C or, better, 90 °C — no laundry, no fabric softener. Many machines have a dedicated programme for this ("drum clean", "machine care"); if yours does not, a 60 or 90 °C cottons cycle does the same job.
A normal dose of powdered heavy-duty detergent is all the additive you need. Powder contains bleach and soda; liquid detergent does not, which makes powder clearly the better choice here. Dedicated washing machine cleaners work similarly but cost more and are not necessary. Skip vinegar: over time the acid attacks rubber seals and metal parts.
If you wash almost exclusively cold, shorten the interval to three or four weeks. If you regularly run 60 °C loads, every six weeks is enough.
The door seal is the actual problem area
The rubber fold around the door collects water after every load, along with hair, lint and detergent residue. It is where black spots appear first on most machines, and it is also the fastest thing on this list to look after: wipe the fold out with a cloth after washing, and leave the door ajar.
Once mould has taken hold inside the rubber, wiping no longer reliably helps — the mycelium grows into the material. At that point it takes a thorough clean with a chlorine-based mould remover or, in bad cases, a replacement seal.
Lint filter and inlet filter
The lint filter sits behind a flap at the bottom front. Every three months, open it, drain the water into a shallow tray and rinse the filter. What collects there — coins, hair, scraps of paper — would eventually jam the drain pump, and that is a repair bill rather than a five-minute task.
The inlet filter is the quieter version of the same problem. Once a year, close the tap, detach the hose, pull out the small mesh screen and rinse it. If the machine takes unusually long to fill, this is usually why.
Common questions
Is vinegar good for cleaning a washing machine?
Acetic acid dissolves limescale reliably, but it also attacks rubber seals, hoses and aluminium parts. For an appliance meant to last a decade that is a poor trade. A maintenance wash with powdered heavy-duty detergent achieves the same without stressing the materials.
Why does my laundry smell musty when the machine looks clean?
The biofilm sits where you cannot see it: the back of the drum, the drain hose, the sump. One or two 90 °C maintenance washes close together usually clear it. If the smell persists, check the lint filter and the detergent drawer next.
Do I need to descale my washing machine?
In hard water areas yes — but usually it happens automatically. Heavy-duty detergents contain water softeners that bind limescale when dosed according to your water hardness. A separate descaler is only needed if you have been under-dosing for years.
Should I leave the door open?
Yes, at least ajar. A closed drum never dries out, and residual moisture is the precondition for mould. If children or pets make that impractical, leaving it open for a few hours after each wash is enough.