The short answer
For the Blomberg DWDT family of dishwashers, the generic answer is not wrong but it is not ordered for these models. What follows is the order that suits this platform. A dishwasher that has stopped cleaning well has almost always lost water pressure at the spray arms, and the usual reason is a filter nobody has opened. Work down in order — the expensive branch is at the bottom and it is also the rarest.
What you observe on these models
- Cleaning has got gradually worse over months — A gradual decline is a filter or a spray arm silting up, not a sudden failure.
- A gritty film on everything rather than particles — Mineral deposit rather than recirculated debris, which is a different branch.
- The top rack is clean and the bottom rack is not, or the reverse — One spray arm is not working, which points at a specific blockage.
- NEAR MISS — there is standing water in the bottom at the end — That is a drainage fault and the drainage page covers it.
Causes, most likely first on this family
- Spray arm holes blocked or arms not rotating — Second: the arms turn on the reaction of their own jets, so a few blocked holes slow them, and a blocked path stops them entirely.
- Filter assembly blocked with food debris — First on the list because a blocked filter both starves the pump and recirculates the debris it was supposed to trap, which produces grit on clean dishes.
- Circulation pump or inlet valve underperforming — Last: when the filter is clean, the arms spin freely and the water is hot, low pressure means the pump or the fill, and that is a technician's diagnosis.
- Why this order is not the brand-generic order — Because the layout differs. On these models the first check is chosen for what it eliminates per minute of work rather than for its standalone probability, and that is what separates a family-level ranking from a brand-level one.
Check in this order, and why
- Note the geography of the dirt — One rack, one region or one side untouched points at a spray arm. Uniform film across everything points at chemistry or temperature.
- Hold a spray arm up and check every hole — Blocked holes are visible against the light and are cleared with a cocktail stick or a fine wire.
- Spin each spray arm by hand — Both arms should turn freely through a full revolution without catching on anything in the racks.
- How to work this list on this platform — Take the steps in order and stop at the first that gives a clear answer. The sequence is built so that the cheap eliminations happen before any disassembly, which is specifically what the construction of these models rewards.
Before you open anything
Safety
Switch off at the spur and close the supply valve first. Water and mains wiring are inches apart in this appliance, and a wet hand behind the kickplate of a live machine is the hazard to avoid.
When to call a technician
If everything reachable with the machine isolated is clean and it still misbehaves, that is the call — and a leak of unknown origin under a worktop should be a call the same day rather than the next weekend.
Other faults covered for this family
What this page generalizes over
This page covers the Blomberg DWDT dishwashers as a family rather than one model. The models in it are close enough to share a diagnosis, but not identical, so where a detail depends on the individual model — a component position, a part number — it is not stated here. The family pages and the brand-level article linked below give the surrounding context.
Lead Appliance Repair Technician · 12 years experience
Experienced technician with 12 years specializing in washing machine and dryer repairs across all major brands.
