What is most likely happening
Standing water in the bottom of a dishwasher is one of the most common complaints in the category, and the cause is usually in the filter, the waste connection or the air gap rather than in the pump. On a B-Flasche dishwasher the order below is what makes this page worth reading — the causes are ranked for this kind of machine, not listed alphabetically.
What owners actually report
- Water left in the base at the end of every cycle — A small amount in the sump is normal on many machines; a visible pool is not.
- Dirty water backing up into the tub — That is coming from the sink waste rather than from the machine — the connection is shared.
- The pump runs audibly without the level dropping — An obstruction downstream rather than a dead pump.
- Water drains away slowly over minutes — A partial restriction in the filter or the hose.
- NEAR MISS — a smell but no standing water — That is residue and biofilm, and it has its own page and its own fix.
Ranked causes on this platform
- Blocked filter and sump — First. The filter is designed to catch food and it does; when it is not cleaned, the water cannot get through it to the pump at all. It is also the one part the owner can lift out by hand.
- Waste hose blocked, kinked or badly looped — Second. The hose has to rise to a high loop before falling to the waste, and when the loop is missing or the hose is crushed behind the machine the water has nowhere to go.
- Disposer knockout plug left in place — Third, and it is famously the cause on a newly installed machine: the waste spigot on a food-waste disposer ships with a plug that must be knocked out before the dishwasher hose is connected.
- Blocked sink trap or shared waste — Fourth. If the sink is slow, the dishwasher will be too, and the fault is in the plumbing rather than the appliance.
What to check first, second, third
- Fill the sink and let it drain — A slow sink and a slow dishwasher share one waste. That single test can save a service call entirely.
- Lift out the filter and look at the sump below it — Most of the diagnosis and most of the fix are in this one step.
- Check the waste hose has a high loop — The hose should rise above the machine before dropping to the waste, which is what stops water siphoning back.
Step by step, within the safe boundary
- Bail out the standing water first — Use a cup and a sponge so the tub is dry enough to work in and so the filter can come out without spilling.
Tools: cup, spongeAbout 20 min
- Remove and clean the filter assembly — Twist the cylindrical filter out, lift the flat screen beneath it and rinse both under a tap with a brush.
Tools: soft brushAbout 25 min
- Clear the sump and check the pump impeller cover — Remove debris by hand, looking for glass, seeds and labels, which are the usual finds.
Tools: glovesAbout 20 min
- Inspect the waste hose route behind the machine — Straighten kinks, restore the high loop and check the connection at the trap or disposer.
Tools: flashlightAbout 30 min
- Confirm the disposer knockout has been removed on a new installation — If the machine has never drained since it was fitted, this is very likely the reason.
Tools: flashlightAbout 15 min
- STOP before removing the drain pump — It is mains-wired in a machine full of water.
Power, water and the limits of owner work
Safety
Power down at the breaker, close both taps, and lay a towel line before tipping the machine to reach the base. Mains terminals sit within finger reach of wet metal in a cabinet this size, so nothing gets probed while the plug is in. The door lock and its wiring stay as built.
When this stops being a home job
This category has one of the highest owner-fix rates on the appliance, largely because the filter is the cause far more often than anything else. Book a visit once the plumbing side is genuinely ruled out. Do not leave standing water in the machine for days while you wait — it goes stale quickly and the smell outlasts the repair.
Other faults on this appliance
What this page does not cover
What you are reading is family-agnostic. It applies to B-Flasche dishwasher units in general and does not claim to describe any single model: service-manual specifics — resistance values, part numbers, harness routing — are exactly what varies between families and are exactly what is left out. If a model-specific page for your unit is linked below, go there first; this page is the fallback when one does not exist yet.
Lead Appliance Repair Technician · 12 years experience
Experienced technician with 12 years specializing in washing machine and dryer repairs across all major brands.
