How does hard water affect commercial dishwashers?

Date modified: 1st June 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.
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Hard water, which contains high levels of minerals like calcium and magnesium, can lead to the buildup of calcium carbonate in commercial dishwashers. This buildup can reduce the efficiency of the dishwasher by clogging spray arms and filters, and by forming a layer that absorbs detergents, which decreases cleaning effectiveness.

Common misunderstanding: Hard water only affects the appearance of dishes, not the dishwasher’s performance.

While hard water can leave spots and film on dishes, it also impacts the dishwasher's performance by clogging and reducing the efficiency of the machine.

Common misunderstanding: If the dishwasher is running, hard water isn’t a problem.

Even if a dishwasher operates, hard water can still cause internal buildups that gradually degrade its performance and increase maintenance needs.

What is calcium carbonate build-up and why is it a problem?

Calcium carbonate build-up is a hard, crusty deposit that forms from the minerals in hard water. It's a problem because it can block water flow in the dishwasher’s components, such as spray arms and filters, and can absorb detergents, making them less effective. This leads to poorly cleaned dishes and potential increases in operational costs due to more frequent repairs and replacements.

Common misunderstanding: Calcium carbonate build-up can be easily wiped off like any dirt.

Unlike simple dirt, calcium carbonate deposits are hard and crusty, requiring specific cleaning agents or manual scrubbing to remove.

Common misunderstanding: Calcium carbonate only builds up if the dishwasher is old.

Calcium carbonate can build up in any dishwasher exposed to hard water, regardless of its age or model.

How can I prevent or manage scaling issues in dishwashers?

To prevent or manage scaling caused by hard water in dishwashers, use water softeners or add salts through the dishwasher’s dosing system to soften the water. Regularly clean and maintain the dishwasher, focusing on removing any visible deposits in spray arms, filters, and other components. Consult with suppliers for specific solutions tailored to your dishwasher if scaling persists.

Common misunderstanding: Regular dishwasher use and detergent alone prevent scaling.

Regular use and detergents do not prevent scaling; specific measures like water softening and targeted cleaning are necessary to manage hard water effects.

Common misunderstanding: Scaling is a minor issue that doesn’t affect dishwasher safety.

Scaling can significantly impact cleaning effectiveness, potentially leading to hygiene issues if not properly managed.

UK Official Guidance