How often should I clean a washing machine and how?

Roughly monthly for a maintenance wash, with the seal and detergent drawer wiped more often. Front-loading machines need this more than top-loaders because their door seal traps water.

The underlying cause of most washing machine odour is modern washing habits rather than neglect. Low temperature washes and liquid detergents leave residue that cold water does not clear, and that residue feeds bacteria and mould. Machines used exclusively at thirty degrees will develop a smell eventually almost regardless of anything else.

A maintenance wash means running the hottest cycle available, empty, ideally with a dedicated machine cleaner or with white vinegar or soda crystals. The heat is the active ingredient; the additive helps but does less on its own. Running one hot wash of towels or bedding periodically achieves much the same thing while being useful.

The door seal is where visible mould appears. Pull it back gently and wipe inside the fold, which holds standing water after every cycle. This is the single most effective habit, and it takes seconds.

The detergent drawer should be removed and rinsed periodically, since undissolved detergent and softener build up in it and in the housing behind.

The filter, usually behind a small hatch at the front bottom, catches debris and holds water. It should be cleaned every few months, and a towel underneath is advisable because water will come out.

Two habits prevent most problems: leave the door and drawer ajar between washes so the drum dries, and avoid overdosing detergent, since excess does not rinse away and becomes the residue causing the problem.