How Citric Acid Cleans a Musty Washing Machine

Citric acid can help to clear mineral deposits, soap residue and some of the grime that builds up inside a washing machine, all of which can contribute to unpleasant-smelling laundry. The drum, detergent drawer and door seal stay damp after cycles and, if they are not cleaned regularly, residue can form a layer in which microorganisms have suitable conditions to grow.

Why does a washing machine start leaving a musty smell?

The smell does not usually result from a single wash. Detergent and fabric conditioner remnants, body oils, lint and moisture can remain in poorly ventilated areas, creating deposits that cling to surfaces. Front-loading machines need particular attention around the door seal, as water can stay trapped in its folds for a considerable time after a cycle.

• Too much detergent or fabric conditioner that is not fully rinsed away
• Water left standing in the folds of the door seal
• A detergent drawer that remains continually damp
• Frequent washing at low temperatures
• Closing the door straight after use

How does citric acid work on drum residue?

Citric acid is particularly effective against mineral deposits left by water, as well as scale that combines with washing-product residue. Its acidity helps loosen this material from internal surfaces, making it easier to remove during an empty cleaning cycle.

It should not, however, be viewed as a product that can remove every form of biofilm or contamination on its own. If visible marks, sludge or a persistent odour are present on the door seal or in the drawer, those sections still need to be cleaned by hand. An internal cycle works best alongside manual removal of built-up dirt.

How to clean the washing machine without adding clothes

The machine should be empty for this process, and the amount of product used must follow the appliance manufacturer's guidance. Different models use different seals, metals and coatings, so a concentrated homemade mixture should not be treated as a universal method for every washing machine.

• Remove every item of clothing from the drum
• Clear lint and visible dirt from the door seal
• Wash the detergent drawer separately
• Run the drum-cleaning programme if the appliance has one
• Once finished, leave the door and drawer open until the inside has dried

Can bleach and citric acid be used together?

No. Citric acid and bleach must never be mixed. Hypochlorite-based products can release irritating and dangerous gases when they come into contact with acidic substances. If the washing machine has been through a bleach cycle, the system must be thoroughly rinsed before any acidic product is used.

It is also inaccurate to say that bleach always damages a machine's rubber seal. Some manufacturers allow it in particular concentrations and cycles, while others advise using products designed specifically for cleaning the drum. The main issue is excessive, concentrated or off-instruction use, which can damage components and shorten their working life.

What prevents the smell returning after cleaning?

Citric acid can remove some existing build-up, but preventing it from returning depends on managing moisture and residue after each wash. Measuring detergent and fabric conditioner correctly reduces the amount of product left in the drum, while leaving the door slightly open helps water trapped on internal surfaces to evaporate.

The seal should also be dried and checked regularly, especially in the lower folds, where water, hair and small objects often remain hidden. When the drum, drawer and seal are kept clean and aired, there is less material available for biofilm to develop, and the musty smell should fade from subsequent loads of laundry.