The short answer
The Blomberg DWS dishwashers are grouped as one platform, and that grouping changes this diagnosis: the same causes apply, in a different order, for reasons of layout. A small amount of water in the sump is normal. A tub with standing water above the filter is not. All of the owner checks here are done with the power off and need nothing but a cup and a cloth.
What you observe on these models
- Water rises during the cycle rather than at the end — The drain is failing partway through rather than at the final pump-out.
- Standing water covering the filter at the end of a cycle — The classic presentation — the cycle ran and nothing left.
- Dirty water appears in the sink when the dishwasher drains — The shared waste line is restricted rather than the machine.
- NEAR MISS — the dishes are dirty but the tub drains — That is a cleaning fault, not a drainage one.
Causes, most likely first on this family
- Filter and sump blocked with food debris — First on the list because it is the only maintenance item in the drain path and it is almost universally neglected.
- Drain pump failed or not being commanded — Last on likelihood and the only branch that needs a meter.
- Drain pump jammed by glass or debris — Fifth: a fragment of glass, a fruit stone or a label can reach the pump and stop the impeller, which then hums without moving water.
- Where this order differs from the brand-generic page — On this family the access route decides the sequence. The cause that moves up is the one reachable without removing a panel on these models, and the cause that moves down is the one that needs the cabinet opened — so the ranking here is ordered by what this platform lets you confirm first, not only by raw likelihood.
Check in this order, and why
- Listen during the drain step — A hum with no level change means obstruction. Complete silence means the pump is not being run, which is a different branch.
- Check the air gap fitting on the worktop if there is one — Lift the cover and look for debris. A blocked air gap stops drainage completely and is often the last place anyone looks.
- Look for the high loop in the drain hose — The hose must rise above the level of the tub before falling to the waste, or the machine siphons and never finishes.
- 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
Switch the machine off at its spur or breaker and close the supply valve under the sink before anything comes apart. Standing water in the tub is not the hazard; the heating element and the terminal block under the machine are.
When to call a technician
Call when the filter, the sump, the spray arms and the waste connection have all been checked and the fault has survived all four. Past that point the next suspects are the drain pump and the control, and both of them are behind the machine.
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.
