The short answer
Start with a disposer knockout plug that was never removed: on a Conservator dishwasher it accounts for more of these than anything else, and the filter or sump blocked is the next thing to rule out. A built-in is plumbed once and then forgotten, which means its faults are usually in the installation under the sink rather than in the machine under the counter. That order is what this page is for, because working it the other way round is how an afternoon gets spent on the least likely cause.
What you observe
- Water standing in the bottom at the end — A small amount is normal on some machines; a bowlful is not.
- It stops part-way through — Usually waiting on water it cannot get or cannot drain.
- NEAR MISS - a smell rather than a performance problem — That is nearly always the filter and the sump, and it is a ten-minute job.
Causes, most likely first on this brand
- The disposer knockout plug never removed — The likeliest cause on this brand: when a machine drains through a waste disposer, a plug inside the disposer inlet has to be knocked out at installation - and a machine that has never once drained since the day it was fitted is nearly always this.
- The filter or sump blocked — Next most likely: labels, seeds and fragments of glass collect where the water leaves, and they stop the drain long before they stop the wash.
- A drain hose without its high loop — Third on the list: the hose must rise above the machine before it falls to the drain, and without that loop the sink drains back into the dishwasher and it never empties properly.
- The sink drain itself backing up — Least likely, and the only one that is not your work: the machine empties into the same pipe as the sink, so a slow sink means a machine that cannot get rid of its water however healthy its pump is.
Check in this order, and why
- Ask whether it has ever drained since installation — A machine that has never drained is a knockout plug until proved otherwise.
- Clear the filter and the sump — Where the water leaves is where the blockage is.
- Look under the sink for the high loop in the hose — No loop means the sink drains back into the machine.
What an owner can safely check
- Ask whether the machine has ever drained since it was installed — If the answer is no and it drains through a disposer, the knockout plug is still in place.
About 10 min
- Reach into the sump with a torch and clear what is in it — Go slowly - broken glass collects there. Check the impeller turns freely.
Tools: torch, glovesAbout 20 min
- Check the drain hose rises above the machine before it falls — Without that high loop the sink drains back into the dishwasher.
Tools: torchAbout 20 min
- STOP HERE if the next step means pulling the machine out or removing a panel — There are live terminals and standing water behind it, and that is where owner checks end.
Before you open anything
Safety
Switch the dishwasher off at its breaker before pulling it out, removing the kickplate or reaching into the sump; a capacitor can hold a charge after the power is off and there is standing water inside the machine beside live terminals. Reach into a sump slowly and with a torch - broken glass finds fingers there more often than anywhere else in a kitchen. Never run a machine with the door interlock defeated.
When to call a technician
Call when the sump is clear, the hose has its high loop, the sink drains freely and the machine still holds water. If the machine is newly installed and has never drained at all, say so when you call - that is an installation fault rather than an appliance fault, and it is fixed in minutes by whoever fitted it.
Nearest pages of this class
What this page does not cover
This page covers full-size built-in dishwashers as a class rather than one model line. Drain routes, air-gap arrangements and sump designs differ by family and by installation, and where a family- or model-specific page exists for your unit it is linked below. Not here: hose figures, capacities and part identifiers.
Lead Appliance Repair Technician · 12 years experience
Experienced technician with 12 years specializing in washing machine and dryer repairs across all major brands.
