The short answer
On the ADB line water left standing at the end of a cycle is usually a blockage rather than a failed pump: work from the sump outwards, because everything that blocks a drain arrives from inside the machine. Only the last cause on the list needs a technician. The order below puts a blocked filter and sump first and a failed drain pump or control last, and that order is the point of the page.
What the owner actually sees
- Standing water in the sump at the end of the cycle — Enough to cover the filter, and it is still there the next morning.
- The drain step hums but nothing moves — The pump is being asked to run and cannot, which usually means something is in it.
- Silence where the drain step should be — The cycle moves on without any attempt to empty the machine.
- Water spits from the air gap at the sink — The blockage is past the machine, in the air gap or the waste connection.
- NEAR MISS - water on the floor rather than in the sump — That is a leak, and the water leak page for this line covers it; a machine can leak and drain perfectly well.
What it usually turns out to be, in order
- A blocked filter and sump — Ranked first on this line: everything that comes off the dishes ends up in the sump, and the filter is what stops it reaching the pump. A matted filter and a sump full of debris leave water standing at the end of every cycle.
- Something jammed in the drain pump — Next, and close behind: on many machines the pump inlet is reachable from inside once the filter is out, which is why it sits above the panel-off causes rather than below them.
- The drain hose routed without a high loop — Then: a drain hose that runs straight down to the waste lets water siphon back into the machine, so it appears never to drain. The pump is fine and the hose is clear; the routing is wrong.
- A failed drain pump or control — Last, and the reason the order matters: it is confirmed by silence at the drain step with everything else proven clear, and it is service work.
Working order, and the reason for it
- Clear the filter and the sump by hand — Lift out the filter assembly, rinse it until the mesh is open, and clear the well underneath of glass, seeds and labels before refitting it.
- Listen to what happens at the drain step — With the machine isolated and the filter out, look into the pump inlet for glass or a fragment of plastic.
- Look at how the drain hose is routed — Follow the hose from the machine to the waste connection and look for a high loop or an air gap. A hose that only goes downhill will siphon back.
Before you open anything
Safety
Unplug the appliance or switch off its breaker before removing any panel or reaching into the pump; a capacitor can hold a charge after the power is off. Broken glass in the sump is the usual injury here, so look before you reach.
Where owner work ends
Call when the filter, sump, drain hose, air gap and waste connection are all proven clear and the machine still holds water: that leaves the pump, the non-return arrangement or the control. Call at once if a breaker trips or you smell burning at the drain step.
Nearest pages of this class
Lead Appliance Repair Technician · 12 years experience
Experienced technician with 12 years specializing in washing machine and dryer repairs across all major brands.
