The short answer
Standing water in a compact machine is usually the shared sink waste rather than the pump. Run the sink tap hard and watch for the water rising inside the dishwasher - that one test tells you which side of the connection you are dealing with.
What you actually see and hear
- Water standing above the filter at the end of every cycle — Either the machine cannot push it out or it is coming back in.
- The sink drains slowly too — A shared blockage, and the dishwasher is only the messenger.
- The pump is audible but the level barely moves — A restriction in the filter, the hose or the connection.
- NEAR MISS - a little water always sits in the sump — Normal. A small amount is left deliberately to keep seals from drying out.
Causes, most likely first on this machine
- Blocked filter and sump — First, because it is where everything that leaves a plate ends up, and a compact filter is small enough to block within weeks.
- Shared sink waste, trap or disposer connection — Second, and the cause most often missed. If the sink is slow, the machine has nowhere to pump to.
- Drain hose loop, kink or a factory knockout plug still fitted — Third. On a recent installation the knockout plug is the classic: the machine has never drained since the day it was fitted.
- Air gap or high-loop failure letting water siphon back — Fourth. It produces a machine that drains and then refills itself, which is confusing until you know it.
- Drain pump or check valve — Last. Pumps fail, but on a shared-waste installation they are outlived by the plumbing in front of them.
Check in this order, and why
- Run the sink tap hard and watch inside the machine — Water rising in the dishwasher is a shared-waste problem, not a pump problem.
- Pull the filter out and check the sump — Cheap, fast, and the most common internal cause.
- Trace the drain hose from the machine to the waste connection — You are looking for a kink, a lost high loop or a sagging run holding water.
- Ask when the machine was installed — A machine that has never drained properly points at the knockout plug rather than at wear.
What an owner can safely check
- Bail the standing water out with a jug and a sponge — Do this before anything else so you can see and reach the filter.
Tools: jug, sponge, towelsAbout 15 min
- Remove and clean the filter and clear the sump by hand — Wear a glove: glass chips end up here.
Tools: gloves, brushAbout 20 min
- Check the sink waste and trap for a shared blockage — Clearing the trap often fixes the dishwasher with nothing else done.
Tools: bucket, wrenchAbout 30 min
- Check the drain hose has a high loop and no kink behind the cabinet — A hose lying flat siphons; a kinked hose blocks.
Tools: torchAbout 20 min
- STOP HERE before removing the pump or opening the sump housing — Wet work next to live terminals, and it is the least likely cause anyway.
Before you open anything
Safety
Unplug the appliance or switch off its breaker before removing any panel - a capacitor can hold a charge after the power is off. A dishwasher sits in a wet cabinet with a live supply behind it, so switch off at the breaker before pulling it out, and turn the water off at the isolating valve under the sink before any hose is touched. Do not lean on an open door to reach the back of the cabinet.
When to call a technician
Call when the filter is clean, the sink drains freely, the hose has a proper loop and the machine still holds water - that leaves the pump or the check valve. Call a plumber rather than an appliance technician if the sink is slow as well, because you have one blockage presenting as two faults. If the machine has never drained since it was installed, say so when you call: that changes the first thing anyone will look at.
Nearest pages of this class
What this page does not cover
This page is written for the slimline built-in dishwasher class, not for one family or model line. Where a brand- or model-specific page exists for your unit it is the more specific answer and it is linked above, so go there first if your machine is named. What is deliberately not here: spray arm and pump part numbers, hose specifications, door spring tensions and control diagnostics, all of which differ by family and belong on the page for that family.
Lead Appliance Repair Technician · 12 years experience
Experienced technician with 12 years specializing in washing machine and dryer repairs across all major brands.
