Why is biofilm a problem in commercial dishwashers?

Date modified: 22nd September 2025 | This FAQ page has been written by Pilla Founder, Liam Jones, click to email Liam directly, he reads every email. Or book a demo to see how hospitality businesses use Pilla to manage food safety.

Biofilm in commercial dishwashers is a problem because it forms a protective layer that harbours harmful bacteria. This can lead to contamination of dishes and utensils, posing a risk to food safety. Biofilm is resistant to regular cleaning chemicals, making it difficult to remove once established.

Common misunderstanding: Biofilm is just a harmless buildup that regular cleaning can handle.

Biofilm is not just any buildup; it's a complex aggregation of bacteria that are embedded in a self-produced protective slime. This makes it resistant to standard cleaning methods, requiring more thorough and specific cleaning procedures to ensure removal.

Common misunderstanding: Biofilm doesn't affect dishwasher performance significantly.

Biofilm can severely impact the efficiency of a dishwasher. It can clog spray arms and filters, leading to poor water circulation and heating, which ultimately compromises the dishwasher's ability to clean effectively.

What does the salmon pink biofilm look like and why is it dangerous?

The salmon pink biofilm appears as a slimy, pinkish residue that can be found on the interior surfaces of a dishwasher, including walls, racks, and spray arms. It is dangerous because it consists of bacteria that can cause foodborne illnesses if they come into contact with dishes and utensils.

Common misunderstanding: The pink colour means it's mild and less harmful.

The pink colour of the biofilm does not indicate mildness; rather, it signals the presence of Serratia marcescens, a bacterium associated with respiratory and urinary tract infections. The colour is a warning sign of potential health risks.

Common misunderstanding: If dishes look clean, they are safe from biofilm bacteria.

Even if dishes appear clean, they can still be contaminated with bacteria from biofilm. The bacteria can transfer from the biofilm to dishes during the washing cycle, making them unsafe despite their clean appearance.

How can I remove biofilm effectively from the dishwasher?

To effectively remove biofilm, manually scrub the affected areas with a stiff brush and use a detergent that is specifically formulated to break down biofilm. It's also important to regularly clean and maintain all parts of the dishwasher, especially the filters and spray arms.

Common misunderstanding: Regular dishwasher detergents are sufficient for removing biofilm.

Regular detergents might not be effective against biofilm. You need specialised cleaners that are designed to penetrate and dissolve the biofilm structure for effective removal.

Common misunderstanding: A one-time deep clean is enough to keep biofilm away.

Removing biofilm requires consistent and regular cleaning routines. Even after a deep clean, biofilm can quickly re-establish if regular maintenance is neglected. Always follow a scheduled cleaning protocol.

UK Official Guidance

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What is the correct wash temperature for a commercial dishwasher?

The correct wash temperature for a commercial dishwasher should be between 55-60°C to ensure that the alkaline chemicals in the detergents are activated effectively.

How does hard water affect commercial dishwashers?

Hard water contains high levels of minerals like calcium and magnesium, which contribute to the buildup of calcium carbonate in commercial dishwashers.

What should the final rinse temperature be in a commercial dishwasher?

The final rinse temperature in a commercial dishwasher should be maintained between 82-88°C to ensure that dishes are not only clean but also sanitised effectively, eliminating harmful pathogens.

How often should dishwasher temperatures be checked and recorded?

Dishwasher temperatures should be checked and recorded twice daily, typically once in the morning and once in the afternoon, to ensure that the dishwasher operates at the correct temperatures required for sanitising dishes effectively. This routine guarantees that the dishwasher maintains the necessary temperatures of 55-60°C for the wash cycle and 82-88°C for the final rinse for effective sanitation.

How should I carry out manual dishwashing when the dishwasher is broken?

When your dishwasher is not working, switch to manual dishwashing by using a three-compartment sink as follows: (1) Wash dishes and utensils with hot, soapy water in the first compartment.

What regular maintenance should be done on a commercial dishwasher?

Regular maintenance of a commercial dishwasher is crucial to ensure efficient operation and maintain hygiene standards. Key tasks include checking and cleaning filters, spray arms, and seals.

What should I do if the dishwasher breaks down during service?

If your dishwasher stops working during service, immediately cease its use to prevent worsening the problem.