The short answer
For the Blomberg DW 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. Poor cleaning is a mechanical problem before it is a chemical one. Water has to reach every surface at pressure, and anything that blocks that path shows up as film and grit. Everything below except the pump is owner work, needs no tools, and takes under an hour.
What you observe on these models
- Dishes at the back are dirty and those at the front are clean — A spray arm that is not rotating through its full sweep.
- 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.
- NEAR MISS — dishes come out clean but wet — Drying is a separate function from washing and involves different parts.
Causes, most likely first on this family
- Detergent, rinse aid or water hardness — Fourth: hard water leaves a mineral film that reads as poor cleaning, and old detergent loses its activity in the box.
- Water arriving too cool — Third, and it presents as film and poorly dissolved detergent rather than as grit.
- 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.
- 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.
- What the family layout dictates here — On these models the components involved are not equally accessible, and the order reflects that. Working it as written means you reach a conclusion with the least disassembly, which matters more on this platform than on a machine where everything is behind one panel.
Before you open anything
Safety
Turn the power off at the isolating switch and close the valve under the sink before touching a fitting. Let a hot cycle cool before reaching into the tub — the heating element and the water are both hot at the end of a programme.
When to call a technician
Stop where the machine has to come out. Unfastening a built-in dishwasher means handling a pressurised supply, a waste connection and a mains circuit in a confined space, and that is a technician's job rather than an owner check.
Other faults covered for this family
Lead Appliance Repair Technician · 12 years experience
Experienced technician with 12 years specializing in washing machine and dryer repairs across all major brands.
