Dishwasher leaving white residue on glasses and plates (Bosch & Zanussi)
✅ Safe to check yourself
This is a common, low-risk check most people can do safely. Always unplug the appliance (or isolate power) before touching internal parts.
Quick TipTake a photo of the appliance's model/serial number sticker now — you'll want it if this does end up needing a part or an engineer.
A chalky white film on glasses and dark plates after a wash is a water hardness issue, not a fault with the machine — the UK has some of the hardest tap water in Europe in many regions (particularly London, the South East, and the East of England), and dishwashers need to be told how hard your local water is.
What to check first
- Find your dishwasher’s water hardness setting (usually in a settings menu, sometimes a dial inside near the salt compartment) and check it matches your actual local water hardness — you can look this up by postcode via your water supplier’s website.
- Check the dedicated water softener salt compartment (separate from the detergent, usually in the base of the tub) is topped up — running low on salt is one of the most common causes of this exact symptom.
- Check you’re using rinse aid, and that its dispenser isn’t empty — rinse aid is what stops water beading and drying into spots/film, separate from the detergent.
- Try a hotter wash cycle occasionally, and avoid opening the door mid-cycle, which can affect the rinse.
When to call an engineer
If salt, rinse aid, and the hardness setting are all correct and the residue persists, the water softener unit itself may need attention — worth a service call, but this is a low-urgency, inexpensive fix.