Dishwasher does not clean the dishes properly

Do the dishes come out with food residue? Are there stains on the glasses? Or are the dishes still wet after washing?

A poor washing result does not necessarily mean that there is something wrong with the dishwasher itself. In a professional dishwasher, the result depends on, among other things, pre-rinse, water quality, temperature, detergent, rinse aid and cleaning the machine.

Here are 8 things you can check if the dishwasher suddenly does not wash properly.

1. Remove food residue before washing

A professional dishwasher is fast, but it is not a garbage disposal.

Larger food residue should be removed before the dishes and kitchenware are put into the machine. In busy kitchens, this typically takes place at a pre-rinse station, where the dishes are scraped off and rinsed before the basket is run through the machine.

The more food residue that enters the machine, the faster the wash water and filters become loaded.

2. Check the filters

The filters collect food residue and other dirt so that it does not circulate freely with the wash water.

If the filters are clogged or not installed correctly, this can affect the washing results.

The filters should therefore be checked and cleaned regularly according to the manufacturer's instructions. In a busy kitchen, it may be necessary to check them several times during the working day.

3. Check the wash arms and nozzles

The wash arms distribute the water around the machine. If a nozzle becomes clogged with food residue, limescale or other dirt, the water cannot reach the dishes as intended.

The result can be areas in the basket where the dishes are consistently washed worse than in other places.

Therefore, check that the wash arms can move freely and that the holes and nozzles are not blocked.

4. Has the wash water become too dirty?

Many professional tank dishwashers reuse the water in the wash tank through several washes. After each wash, fresh water from the final rinse is added, but a large part of the wash water is recirculated.

This is one of the reasons why professional machines can wash quickly and with relatively low water consumption per basket.

However, if large amounts of food residue enter the machine, the tank water gradually becomes more contaminated.

If the water is very dirty, the tank should be emptied and the machine cleaned and filled with clean water again.

5. Check the detergent

More detergent does not automatically result in cleaner dishes.

Too little detergent can give an inadequate washing result, while too high a dosage can also cause problems and unnecessary chemical consumption.

Many professional dishwashers dose the detergent automatically. If the result changes, it may therefore be relevant to check whether the container is empty, whether the hose is correctly positioned in the container, and whether the dosing system is working.

Always use a detergent intended for professional dishwashers. Ordinary hand washing detergent must not be used in the machine, as excessive foaming can disrupt the washing process.

6. Check the rinse aid

Rinse aid is used during the final rinse and helps the water drain from the dishes.

If the dosage is too low, the result can be wet dishes and water spots. Conversely, too high a dosage can result in streaks or a dull surface.

If the glasses suddenly dry worse than usual, the rinse aid is therefore one of the first places it makes sense to check.

7. Check the water quality

If the dishes are clean, but the glasses have white spots or deposits, the problem may be due to the water rather than the sink itself.

Minerals in the water can remain on glasses and dishes when the water evaporates. The problem is typically more visible on glasses, cutlery and dark dishes.

Water treatment can therefore be important both for the protection of the machine and for the visual result after washing.

If the problem is primarily white spots and limescale, you can read our guide on limescale and water treatment in industrial dishwashers.

8. Clean the dishwasher itself

A dishwasher does not automatically become clean just because it washes dishes all day.

Food residue, grease and limescale can accumulate in filters, wash arms, nozzles and inside the wash chamber, among other things.

The machine should therefore be emptied and cleaned according to the manufacturer's instructions. How often this is necessary depends, among other things, on how much the machine is used and what is being washed in it.

White spots, streaks or food residue?

The type of problem can give a clue as to where to start troubleshooting.

Food residue on dishes: Check the pre-rinse, filters, wash arms, nozzles and tank water.

White spots or deposits: Check water quality and water treatment.

Wet dishes: Check rinse aid and final rinse.

Streaks or dull surface: Check the dosage of soap and rinse aid.

The result gets worse during the day: Check the tank water, filters and the amount of food residue that enters the machine.

When should you have a technician look at the machine?

If the general points have been checked and the washing result is still poor, the problem may be technical.

For example, it may be relevant to examine the temperature, water supply, dosing system, pumps or other components in the machine.

In this case, troubleshooting should be carried out by a service technician rather than changing the machine's technical settings yourself.

Is the problem the dishwasher itself?

If the machine is working properly, but consistently cannot keep up with the kitchen's dishes, the problem may be the capacity rather than the washing result.

If you are about to replace the machine, you can see our industrial dishwashers. Here it is particularly important to choose based on the amount of dishes to be washed during the busiest period and not just the number of guests in a whole day.