The short answer
A Black+Decker WQP dishwasher that leaves water behind is telling you the path out is blocked somewhere along its length. The path has four parts — sump, hose, air gap or disposer connection, and pump — and only the last needs a technician. This page works along the path in order, because that is the order that finds it fastest. The WQP key covers more than one build, and for this fault the difference shows in whether your unit has an air gap cap on the worktop.
What you observe on these models
- Water standing in the tub at the end of the cycle — Enough to scoop rather than a film in the sump recess.
- The sink fills while the machine empties — The shared drain line beyond the machine is restricted rather than the machine itself.
- Gurgling from the sink during the drain — Often the first sign, weeks before water is left behind.
- Stale water odour on opening — It usually arrives with a filter that is overdue.
- A partial drain that leaves a shallow layer — A restriction rather than a blockage — more typical of the hose route than of the sump.
- NEAR MISS — a film of water always in the sump recess — Judge by what covers the tub floor, not by the recess.
Causes, ranked for the WQP build
- The filter and sump are blocked — It leads on filter builds, because everything the machine washes off has to pass this point and nothing tells you when it stops passing. Lifting the filter out takes seconds and settles the question.
- The drain hose is kinked, blocked or has lost its high loop — It ranks high because it is common, invisible and free to fix.
- The disposer knockout plug or the air gap is blocking the outlet — This is the top cause on a machine that has never drained since it was fitted, and it is not a fault at all — it is a plug that was never removed.
- The check valve or the drain path inside the machine — Mid-list: it explains water returning to the tub after a good drain, which is a different pattern from water that never left.
- The drain pump is jammed or has failed — Last, because every cause above it is reachable without tools and this one is not.
Check in this order, and why
- Scoop the water out and look at the sump — Use a jug and a cloth, and watch for glass.
- Inspect the filter and the sump recess — A torch makes the difference between looking and seeing.
- Follow the drain hose under the sink — Second because it is the next part of the same path.
- Check the disposer connection or the air gap — A knockout plug left in place is the reason a new machine has never drained once.
Before you open anything
Safety
Switch the machine off at its breaker before reaching behind the kick plate or the door panel — water and mains wiring share the same small space in a dishwasher, and a capacitor can hold a charge after the power is off. Leave the door latch and its switch exactly as they are: the machine is meant to stop the moment the door opens.
When to call a technician
Call when the filter, the hose route and the waste connection are all clear and the tub still holds water — that leaves the pump and the parts under the tub. Call sooner if you can hear the pump hum without moving water, or if there is glass in the sump: a fragment in the impeller is a common cause and a bad thing to fish for by hand.
Other faults covered for the WQP models
Lead Appliance Repair Technician · 12 years experience
Experienced technician with 12 years specializing in washing machine and dryer repairs across all major brands.
