What is actually going on
A WQP line machine whose pump hums without moving water has an obstruction at the impeller, and on these models the impeller is reachable once the filter column is out. That is why the owner-side checks on this platform go one step further than the brand-generic page does.
What you are seeing
- A smell of stale water from the tub — Water that has been standing for days goes stale, and the smell usually arrives before anyone notices the water.
- The sink gurgles while the dishwasher drains — Shared waste that cannot take the flow. The machine is fine and the plumbing is not. This is where the WQP line differs from the brand’s other lines.
- Dirty water is redeposited on the load — Water that never left the tub is pumped back over the next fill, so the load comes out worse than it went in.
- The pump runs but the level never drops — Noise without flow means an obstruction rather than a failure.
- Water is standing in the sump when the cycle ends — Enough to cover the filter plate, and it does not fall away when the door is opened.
- NEAR MISS — water on the floor rather than in the tub — Outside the machine is a leak; inside it is drainage.
- NEAR MISS — a small pool in the sump recess — Many machines keep a little water in the recess by design, to stop the seals drying out.
The ranking that matters
- A kinked or trapped drain hose — Ranked first on this platform. The hose leaves the cabinet high and turns immediately, so pushing the machine into a tight housing pinches it. It is one of the few places the models listed in the table on this page genuinely diverge.
- Debris packed into the filter stack — Second. A partial block starves the pump of flow before it stops it outright, which is why the fault creeps up over weeks.
- An obstruction at the pump impeller — Third in the order. Hard objects that get past a damaged filter end up here, and the jam is audible. The WQP line behaves the same way here from one model to the next.
- A failed drain pump — Less common than the three above. Genuinely possible, and genuinely last: every cheaper cause imitates it.
- A drain hose without a high loop — Near the bottom of the list. A hose that runs flat or downhill lets waste water siphon back into the tub between cycles.
Check in this order, and why
- Listen at the drain step — The sound splits the causes in two before anything is opened.
- Bail the standing water out first — A jug and a sponge. Nothing below can be seen or reached until the sump is empty. The WQP line puts this within reach without a teardown.
- Lift the filter stack and inspect it — Every layer, in order. The debris in it usually explains the whole fault.
- Clean the air gap if the installation has one — Lift the cover and clear the cylinder; it silts up like any other trap.
Read this before you start
Safety
Power off, water off, then panels. A dishwasher that has just finished a cycle is hot inside and its sump water can carry glass fragments, so wear gloves and bail with a jug rather than reaching in blind.
Models in the WQP family
Reference| Model number | Family key |
|---|---|
| WQP12-77E1B-US | bertazzoni:dishwasher:wqp |
| WQP8-7740-US | bertazzoni:dishwasher:wqp |
The line between a fix and a call
Call when the filter is clean, the impeller is clear, the hose is straight with a high loop and the sink runs freely — what is left is the pump or the control, and both need the machine out.
Nearby pages
Lead Appliance Repair Technician · 12 years experience
Experienced technician with 12 years specializing in washing machine and dryer repairs across all major brands.
