The short answer
A dishwasher that leaves water in the base usually comes down to one thing: the filter and sump are blocked. Next on the list: the air gap or the disposer connection is blocked. The first check needs a sponge and a cup and nothing else, and it resolves most of these.
What you observe
- Water standing in the base at the end of the cycle — The cycle ran; the water never left.
- Water standing in the base at the end of the cycle — The cycle ran; the water never left.
- It has never drained well since it was installed — A fault present from day one is an installation fault.
- Dirty water appears in the base between cycles — That is water coming back, not water failing to leave.
- NEAR MISS — a little clean water in the sump between cycles — A small amount there is normal and keeps the seals from drying out.
Causes, most likely first on this machine
- The filter and sump are blocked — First on this machine. Everything the dishes carry ends up in the sump, and the filter is what stops it reaching the pump. Let it pack solid and the water has nowhere to go — the machine finishes its cycle and leaves an inch of grey water in the base.
- The air gap or the disposer connection is blocked — Ranked here because the fault is in the plumbing rather than the appliance, which is where people look last.
- The drain hose is kinked or has lost its high loop — Ranked here because it is free to check and it dates from the last time the machine or the cabinet was disturbed.
- Something is jammed in the drain pump — Last of the pump causes, and it is why the filter has to be seated properly every time.
Check in this order, and why
- Lift out the filter stack and clear the sump beneath it — Everything the dishes carry ends up here.
- Check the air gap and the disposer spigot for a blockage — A knockout plug left in place blocks the drain permanently.
- Follow the drain hose and check it rises before it falls — Without a high loop the machine siphons or backfills.
- Listen for a hum at drain time with no water moving — A hum means the pump is trying; silence means it is not.
What an owner can safely check
- Switch the machine off and bail the base out — A sponge and a cup will empty a sump in a few minutes and let you see it.
Tools: sponge, cupAbout 20 min
- Remove the filter, bail the sump and clear any debris — A sponge and a cup get the last of it out.
Tools: sponge, cupAbout 25 min
- Clear the air gap cap and check the disposer spigot is open — Look for a moulded knockout plug still in place.
Tools: torchAbout 25 min
- Straighten the hose and clip it high under the worktop — It must rise above the tub before it drops to the waste.
Tools: torchAbout 20 min
- STOP HERE before removing the pump or its housing — That means the machine out of its cabinet with the power and water off.
Before you open anything
Safety
Switch the machine off at its spur or breaker before removing any panel, and close the isolating valve before touching a hose. A capacitor can hold a charge after the power is off. Broken glass ends up in the sump on any machine. Wear gloves to clear a filter, and shut the isolating valve before disturbing a hose.
When to call a technician
Call once the filter and the sump are clear, the hose has its high loop, any air gap or disposer connection is open, and the water still will not leave. At that point the pump comes out. Call immediately if you smell burning from the base — a jammed pump motor can cook itself trying.
Nearest pages of this class
What this page does not cover
This page is written for the brand and the machine class, not for one family or model line. Where a family- or model-specific page exists for your machine, it is the more specific answer. Deliberately absent: programme charts, place settings, spray-arm and pump part identifiers and wiring colours, which differ between the freestanding and integrated families.
Lead Appliance Repair Technician · 12 years experience
Experienced technician with 12 years specializing in washing machine and dryer repairs across all major brands.
