The short answer
Standing water is usually the installed drain hose or the filter, not the pump. Check the hose has a proper high loop and that the sink drains freely before opening anything on the machine.
What you actually see and hear
- Water above the filter at the end of every cycle — It could not pump out, or what it pumped came back.
- Water returns between stages — A siphon, from a hose without a high loop.
- The sink drains slowly too — A shared blockage, and the machine is only reporting it.
- A smell from the tub between washes — Standing water and a loaded filter together.
- NEAR MISS - a small amount always in the sump — Normal and deliberate.
Causes, most likely first on this machine
- Drain hose without a high loop, or kinked — First. Without the loop, waste water siphons back; with a kink, nothing leaves at all. Both are installation faults rather than appliance ones.
- Filter and sump loaded — Second. On a machine with a manual filter that is rarely cleaned, this arrives steadily.
- Sink waste, trap or disposer connection — Third. The machine drains into the sink waste, so a slow trap is a slow dishwasher.
- Disposer knockout plug still fitted — Fourth, and unmistakable: the machine has never drained since installation.
- Debris in the drain hose itself — Fifth. Less common, but a hose that has held water for years collects a lining.
- Drain pump or check valve — Last. Pumps do fail, but the installation in front of them fails far more often.
Check in this order, and why
- Run the sink tap hard and watch inside the machine — Water rising in the tub means a shared-waste problem.
- Pull the machine forward and look at the hose route — High loop, no kink, secure connection. That is what you want to see.
- Pull the filter and clear the sump — The most likely internal cause.
- Ask when the machine was installed and by whom — A machine that never drained properly points at the installation.
What an owner can safely check
- Bail the standing water out with a jug and a sponge — First, so you can reach the filter.
Tools: jug, sponge, towelsAbout 15 min
- Remove and clean the filter and clear the sump by hand — Wear a glove for glass chips.
Tools: gloves, brushAbout 20 min
- Check the drain hose rises to a high loop and is not kinked — This is the fault more often than anything inside the machine.
Tools: torchAbout 25 min
- Clear the sink trap — A slow sink is a slow dishwasher, and clearing it often fixes both.
Tools: bucket, wrenchAbout 30 min
- Run a short cycle and watch the drain stage — Confirm the fix before reassembling anything.
About 30 min
- STOP HERE before removing the pump or opening the sump housing — Wet work near live terminals and the least likely cause.
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 connection behind it, so switch off at the breaker before pulling it out and close the isolating valve under the sink before touching any hose. A plastic tub holds heat, so let a hot cycle cool before reaching inside.
When to call a technician
Call when the hose is correctly looped and clear, the sink drains freely, the filter is clean and the tub still holds water - that leaves the pump or the check valve. Call a plumber instead if the sink is slow as well. If the machine has never drained since it was installed, say so when you book: that points straight at the hose routing or a disposer knockout plug and can save a wasted diagnostic visit.
Nearest pages of this class
What this page does not cover
This page is written for the plastic-tub 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, heater ratings, 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.
