How to Delime a Commercial Dishwasher

/ Commercial Dishwashers, Preventative Maintenance & Cleaning / October 17

A dishwasher is a vital part of a commercial kitchen, making cleanup as easy as possible. Your customers may forgive an overcooked steak, but they probably won’t forgive dirty dishes. While a dishmachine or warewasher should keep items sparkling clean, eventually lime buildup may form inside the unit. This can cause mineral deposits to form on dishes, glasses and silverware.

We’ve talked about the importance of water filtration and the damaging effects of water hardness. While it’s advisable to deal with water hardness using a softening system rather than repeated deliming cycles because the acid can erode a machine over time, you should occasionally delime if you notice abundant scale buildup. Here are some easy steps for deliming a commercial dishwasher.

Step 1. Find the right cleaner – If the dishmachine uses chemical sanitizers like chlorine, iodine, or quaternary ammonia, consult a technician or an owner’s manual to verify chemicals used for deliming. Mixing chemicals can create a noxious gas or acid which could be harmful to humans or damage your machine.

Step 2. Drain the tank and fill with fresh water – Even if the machine has an automatic delime cycle, you may have to manually drain the tank and fill with fresh water before adding the deliming agent. Check out the owner’s manuals to learn more about your model.

Step 3. Add deliming solution – After filling the machine with fresh water, add the correct amount of deliming solution as recommended by the chemical manufacturer.

Step 4. Run the machine – Close the door and run the machine for the time recommended by the manufacturer’s instructions. Some machines allow you to disconnect the timing mechanism and run the machine indefinitely. Others may require that you run multiple cycles. Check your owner’s manual to see which is required.

Step 5. Inspect the inside – After the cycle, inspect the inside of the machine. If it’s not delimed, cycle again, following the deliming solution’s instructions.

Step 6. Remove residue – If the machine is delimed, drain and refill the machine. Run for 10 minutes to remove residual deliming solution.

Step 7. Drain and refill – Once the residual solution is gone, drain and refill the machine.

Please contact a local authorized service agent who can help with these specific units and all your commercial kitchen equipment needs.


  1. Jerry Bauer says:

    Great advice and I hope to add some more insight.

    Yes it will shorten the life of the heaters.However because the heaters have to work so much harder, you are wasting a substantial amount of energy which is usually electric.

    Also you advise to remove the sanitizer, because for example it is a chlorine base product and will mix with the acid and cause a gas. However you also need to remove the main detergent as well because it counteracts with the descaler. Yes, consult with the person who handles the chemicals you purchase will be best.

    That’s why you need support, which is not usually something you can get from a big box store.

    Finally we at CleanseTec normally put up wall charts and add reminders to management because it is something we believe in so much.

  2. Elaine Powis says:

    All of our projects throughout the UK have water filters specified for every machine using water i.e ice machines, all types of coffee machines, combi ovens, water boilers etc & this is due to water being pumped from different locations in the country. Although the water may not be hard when tested it is uncertain if this could change in the future.

    Softened water cannot be used for drinking due to the chemical content & that is another factor we have to take into consideration when designing the catering facilities within a project. If a building has a softened water supply we insist that the catering facilities have their own water supply & clients are very understanding.