The short answer
On a Bosch dishwasher, water left in the bottom at the end of a cycle usually comes down to a jammed drain pump rather than anything deeper in the machine: the drain pump stalls on debris rather than burning out, so the machine hums at the drain step and gets nowhere. That keeps it an owner check first, not a service call. Start here: look for water in the base pan, because a Bosch latches on its base-pan float and runs its drain pump until the pan is dry.
What you are seeing
- Standing water in the sump when the cycle finishes
- Water that reappears in the tub after the kitchen sink is used
- A hum at the drain step with nothing moving
- Not this fault: Clean water in the sump on a machine that has not run, which is a weeping fill valve
- Not this fault: A wet floor rather than a wet tub, which is a leak
- Body: Bosch builds this dishwasher as a stainless tub that dries by condensation rather than with a heating element, sealed by a single-piece door gasket, with an integrated drain pump and a base-pan float that latches the machine into a continuous drain. That architecture decides which of these you see first.
- Also check note: If these fit better, the fault is a different one.
Likely causes, in order
- A jammed drain pump — Why this rank: The Bosch drain pump is integrated into the sump rather than hung below it, so it stalls on debris and hums instead of burning out.
- A blocked filter stack — Why this rank: The Bosch filter cylinder unthreads with a fine screen behind it, and a blocked screen starves the drain path as well as the wash.
- A stuck drain check valve — Why this rank: The Bosch check valve sits in the pump outlet and sticks once debris has passed it, letting the sink drain back into the tub.
- No high loop in the drain hose — Why this rank: A Bosch is normally installed with a high loop clipped to the cabinet.
- The disposer knockout plug still fitted — Why this rank: A newly installed disposer keeps a plug in its dishwasher inlet.
- Body: Ranked for a Bosch dishwasher specifically.
What to check, in order
- Body: The order follows the ranking, and the ranking follows the platform. First: clear the sump and look for a foreign object at the impeller. It goes first because the Bosch drain pump is integrated into the sump rather than hung below it, so it stalls on debris and hums instead of burning out. Second: unthread the filter and hold the fine screen to a light. With the first check clean, this is what the Bosch platform makes next most likely. Third: look for standing water that reappears after the sink is used. Only after those three is it worth reaching for no high loop in the drain hose: it costs more to get at, and it does not explain the first three coming back clean.
Checks you can make
- Listen to the machine with the door shut and nothing selected. A drain pump running on its own means the base-pan float has tripped and there is water under the tub. — Tools: none — Time: about five minutes
- Bail the standing water out of the sump with a cup and a sponge until you can reach the filter, and note whether the water is clean or full of debris. — Tools: cup, sponge, bucket — Time: about fifteen minutes
- Slide the machine out on a towel and look along the floor under the tub for a damp line. On this platform a leak reaches the pan without ever appearing at the door. — Tools: towel, flashlight — Time: about twenty minutes
- Take out the lower rack, unthread the filter assembly and lift out the fine screen behind it. Rinse both under a running tap until light passes evenly through the mesh, then refit and lock the cylinder. — Tools: none — Time: about ten minutes
- Body: Stop at the first step that would need a meter on live terminals or a sealed assembly opened.
Before you open anything
Safety
Switch the machine off at its breaker, or unplug it, before removing any panel. Unplug the appliance or switch off its breaker before removing any panel. A capacitor can hold a charge after the power is off. Work with the floor dry and stand on something dry. Water on the floor is part of the electrical hazard, not separate from it.
When to call
The line is not difficulty, it is what the next step costs and risks. Call when: the sump and pump are clear, the hose is unrestricted and the pump still does not move water the machine hums at the drain step with a clear impeller
Nearest pages
What this page omits
This is generalized information: it ranks causes for the Bosch dishwasher range as one platform, not for a single model. Where a page exists for your specific model it is the more specific one and takes precedence over this. The narrower pages below cover the other presentations of this symptom.
Entries: - [Bosch Dishwasher: Door, Latch or Seal Fault](/blog/bosch-dishwasher-door-seal) - [Bosch Dishwasher: Water Leak](/blog/bosch-dishwasher-water-leak)
Related pages
Lead Appliance Repair Technician · 12 years experience
Experienced technician with 12 years specializing in washing machine and dryer repairs across all major brands.
