JD CATERING EQUIPMENT TROUBLESHOOTING GUIDE
Why Is My Commercial Dishwasher Leaving Marks?
Cloudy glasses, white marks, streaks or water spots after a wash? Here are some of the most common causes of marked crockery and glassware from a commercial dishwasher — and what to check first.
01
Why is my commercial dishwasher leaving marks?
Marks after washing do not necessarily mean that your commercial dishwasher needs replacing. The appearance of the mark can often give you a useful clue about what is happening during the wash and rinse cycle.
Hard water or limescale
Mineral deposits from hard water can be left behind as water evaporates from glasses, plates and cutlery.
Rinse or drying issue
Poor rinsing, incorrect rinse-aid dosing or water remaining on items as they dry can contribute to visible spotting.
Chemical dosing
Too much or too little detergent or rinse aid may affect the finish after washing.
Wash performance
Blocked wash arms, dirty filters, poor loading or inadequate pre-scraping may prevent effective cleaning.
Look closely at the type of mark before changing settings or chemicals. White mineral deposits, greasy streaks and food residue can have very different causes.
02
What causes white marks on glasses and plates?
Hard water is one of the first things worth investigating when a commercial dishwasher repeatedly leaves white or chalky deposits.
Hard water contains dissolved minerals. When water is heated and evaporates, these minerals can contribute to deposits on ware and inside the dishwasher.
Limescale can also affect components within the machine over time, which is why suitable water treatment can be particularly important in hard-water areas.
Visible scale around internal surfaces, heating areas or wash components can be another indication that water hardness needs investigating. Follow the manufacturer's cleaning and descaling instructions for your exact machine.
03
Could rinse aid be causing marks?
Rinse aid is designed to support the final rinse and drying process, helping water drain from the surface of crockery and glassware.
If the rinse-aid container is empty, the dosing is incorrect or the dosing system is not operating as intended, you may notice spotting, streaking or poorer drying results.
Check the rinse-aid supply
Make sure the chemical container has not run empty and that the correct product is being used for the machine.
Check the feed tube
Where accessible to the operator, look for obvious kinks or an incorrectly positioned chemical tube.
Check the manufacturer's settings
Do not randomly increase chemical dosing. Follow the machine and chemical supplier's recommended setup.
04
Can too much dishwasher detergent leave marks?
Incorrect detergent dosing can contribute to poor wash results. More chemical does not automatically mean cleaner crockery.
The correct detergent and dosing arrangement depends on the dishwasher, water conditions, chemical product and operating requirements.
- Check that the correct chemical is connected.
- Make sure detergent has not run out.
- Check accessible tubes for obvious problems.
- Follow the chemical supplier's dosing guidance.
- Avoid manually adding extra chemical unless instructed.
- Investigate sudden changes in wash quality.
05
Does my commercial dishwasher need a water softener?
It may. Water hardness varies by location, and many commercial dishwashers benefit from suitable water treatment where the incoming supply is hard.
Depending on the machine, water treatment may involve an integral softener, an external water softener or another manufacturer-approved system.
If your dishwasher already has a water softener, check that it is being operated and regenerated in accordance with its instructions. A softener cannot provide the intended protection if it is not being maintained correctly.
Suitable water treatment isn't only about improving the appearance of glasses and crockery. Controlling scale can also help protect components inside compatible commercial warewashing equipment.
06
What should I clean if my dishwasher is leaving marks?
If wash quality has gradually become worse, routine cleaning is a sensible place to start.
Always follow the cleaning procedure for your specific dishwasher. Common user-serviceable areas may include:
- Wash tank filters
- Removable wash arms
- Rinse arms where specified
- Wash jets and nozzles
- Internal tank surfaces
- Door seals and accessible edges
- Strainers
- Removable debris traps
A heavily contaminated filter can reduce wash performance and allow debris to remain in the wash water. Follow the manufacturer's instructions for removal and cleaning.
07
Can loading a commercial dishwasher incorrectly cause marks?
Yes. Even a correctly functioning dishwasher may give disappointing results if water cannot reach every surface properly.
Avoid overcrowding baskets or positioning large items where they can obstruct wash or rinse spray.
- Do not overcrowd baskets.
- Remove excessive food debris first.
- Allow water to reach all surfaces.
- Use the correct basket for the ware.
- Avoid items nesting together.
- Check that wash arms can rotate freely where applicable.
08
Commercial dishwasher marks: quick diagnosis
| What you see | Possible cause to investigate | First check |
|---|---|---|
| White chalky marks | Hard water or scale | Water treatment and softener operation |
| Water spots | Rinse or drying performance | Rinse-aid supply and correct loading |
| Streaks | Chemical dosing or rinse performance | Detergent and rinse-aid setup |
| Food still attached | Blocked jets, dirty filters or loading | Clean user-serviceable components |
| Greasy finish | Wash performance, chemical or loading issue | Cleaning, chemical supply and wash process |
| Problem suddenly appears | Changed chemical, empty container or machine fault | Check what has changed since the previous service |
09
When should I call a commercial dishwasher engineer?
If cleaning, loading, chemical supply and the normal operator checks do not resolve the problem, the machine may require professional investigation.
Stop and seek appropriate assistance if there is an electrical fault, significant leak, unusual smell, repeated alarm, failure to reach its intended operating conditions or another condition that may make the machine unsafe.
Do not remove electrical covers, alter internal components or attempt repairs outside the manufacturer's user instructions. Commercial dishwashers combine electricity, hot water and chemicals and should be serviced by appropriately competent personnel.
10
Commercial dishwasher troubleshooting FAQs
Why is my commercial dishwasher leaving white marks?
White or chalky marks can be associated with minerals in hard water or limescale. Check the water treatment system, any fitted softener and the manufacturer's maintenance requirements.
Why are my glasses cloudy after going through the dishwasher?
Cloudiness can have several causes, including mineral deposits, chemical dosing, rinse performance or the condition of the glassware itself. Start by checking water treatment, rinse aid and the machine's normal cleaning requirements.
Can too much rinse aid leave streaks?
Incorrect rinse-aid dosing can affect the finish of washed items. Follow the dishwasher and chemical supplier's recommended dosing settings rather than adjusting the dose without guidance.
Does a commercial dishwasher need a water softener?
This depends on the dishwasher and local water conditions. In hard-water areas, suitable manufacturer-approved water treatment may be important for both wash results and scale control.
Why is my commercial dishwasher suddenly not cleaning properly?
Check for simple changes first, such as an empty detergent or rinse-aid container, dirty filters, blocked user-cleanable wash components, incorrect loading or a change in operating procedure. Persistent problems may require an engineer.
How often should I clean a commercial dishwasher?
Follow the cleaning frequency and procedure specified by the manufacturer for your exact machine. High-volume operations may also need routine checks during service where specified.