Commercial Dishwasher Cleaning and Descaling

Posted by Shirley Langridge on October 27, 2026

A structured commercial dishwasher cleaning routine keeps glassware sparkling, plates food-safe and callouts to your kitchen engineer to a minimum. Pass-through and under-counter dishwashers work hard, and without daily attention they turn into breeding grounds for limescale and starch build-up. In London’s hard-water postcodes, an untreated boiler on a Winterhalter or Hobart machine can seize inside 18 months. A ten-minute nightly routine and monthly descale extends that life to five, seven or even ten years.

Quick answer

Commercial dishwashers need daily draining and filter cleaning, weekly deep cleaning of wash and rinse arms, and monthly descaling in hard-water areas. Use only approved detergent, rinse aid and descaler (Winterhalter, Hobart, Ecolab or Diversey) to protect seals and pumps.

Understand the machine

Pass-through, hood-type and under-counter dishwashers all work the same way: fill, wash, rinse, drain. The rinse cycle typically holds water at 82-85 C to sanitise, which is why hard water leaves scale in the boiler. Common commercial brands in London include Winterhalter, Hobart, Meiko, Classeq and Maidaid, and while every model is slightly different the underlying cleaning routine is the same.

Key components you will interact with:

Wash arms with spray nozzles.
Rinse arms fed from the booster tank.
Coarse filter and fine filter in the sump.
Detergent and rinse-aid dosing pumps.
Door seal or hood gasket.
Softener salt reservoir (on integrated-softener models).

Tools and products you’ll need

Manufacturer’s detergent and rinse aid.
Approved descaler (matched to your machine).
Softener salt (tablet grade, not table salt).
Cocktail sticks or fine wire for clearing nozzles.
Two microfibre cloths.
Stainless steel polish for exterior.

Daily cleaning at end of service

Never leave the machine full of dirty water overnight. Do this every night without exception.

Drain the wash tank.
Remove and rinse the coarse and fine filters.
Wipe out the sump with a cloth.
Lift out the wash and rinse arms and rinse under a tap.
Poke the nozzles with a cocktail stick to clear blocked holes.
Wipe seals with a warm soapy cloth.
Leave the door or hood open to dry overnight.
Check dosing tube reservoirs; refill if low.

Weekly deep clean

Once a week, take the machine down for a longer clean.

Soak the wash and rinse arms in hot detergent water.
Wipe the interior walls with a non-caustic degreaser.
Check the seals for splits and clean under lips.
Empty the salt reservoir if your machine has one, and refill.
Confirm detergent and rinse-aid dosing rates are correct.
Run a self-cleaning cycle if the model has one.

Descaling in hard-water areas

London water is hard, typically 250-350 mg/l CaCO3 across most postcodes. Limescale builds up on wash arms, boiler elements and inside the boiler tank; unchecked it insulates the element, drops rinse temperature and eventually cracks the boiler.

Signs your machine needs descaling:

Cloudy glassware after wash.
Wash cycle taking longer than usual.
Rinse arm nozzles blocked despite cleaning.
Visible white deposits on the wash tank walls.
Rinse temperature warning on the display.

Use a proper commercial dishwasher descaler at the frequency the manufacturer states, typically monthly without a softener and quarterly with one. Run the machine empty, dose the descaler into the wash tank, run a full cycle, then rinse with two clean cycles before reloading with dishes. Never mix descaler with detergent.

Cleaning the exterior and racks

Wipe the stainless steel with a dedicated stainless polish once a week. Wash dish racks in the sink weekly to remove build-up in the corners. Rinse detergent-dosing hoses per your service agreement. Check the drain hose is not kinked; slow draining accelerates scale build-up.

Common mistakes to avoid

Using table salt in the softener reservoir; it clogs the resin.
Skipping the daily drain to save time; scale sets overnight.
Using bleach inside the machine; it damages stainless components.
Refilling detergent from generic containers with the wrong dosing.
Ignoring the amber “descale required” warning and losing warranty cover.

Booking a service

Even the best cleaning routine cannot replace a yearly service by an authorised engineer. The service should include element check, boiler flush, dosing calibration and thermostat test. Keep the service report on file for at least two years; some insurers request it after any drainage claim.

Water treatment matters

The single biggest lever in London kitchens is a proper base-exchange water softener or reverse-osmosis unit on the incoming supply. Ask your dishwasher supplier for their recommendation; the payback in reduced descaling, better wash results and longer machine life pays for the softener within 18 months in most cases.

Frequently asked questions

How long should a commercial dishwasher last?

With daily cleaning, monthly descaling and a yearly service, expect 8-12 years from a mid-range machine and 12-15 years from premium Winterhalter or Hobart units. Neglected machines fail within 3-5 years.

Can I use a home dishwasher tablet in a commercial machine?

No; the chemistry is wrong and the doser will over- or under-supply. Only use bulk detergent designed for your machine and doser.

What temperature should the rinse be?

UK guidance is at least 82 C at the plate for a minimum of 10 seconds to ensure sanitisation. Machines self-check but a hand thermometer verifies the reading if in doubt.

Cost of neglect

A boiler element replacement is 250-450 GBP. A full boiler replacement is 800-1,500 GBP. A new machine can cost 3,000-6,000 GBP. Weigh those figures against 10 minutes a night for filter cleaning, and the case for a strict routine is obvious.

Conclusion

Commercial dishwashers are workhorses that reward attention. When your kitchen deep clean is booked, our commercial kitchen cleaning service covers the dishwasher exterior, sump and arms alongside ovens, canopies and combi ovens. See our coverage to plan a bespoke visit.