Direct answer: If your Bosch dishwasher is not draining, the most common cause is a blockage in the filter, sump area, drain hose, or sink-side drain path. Start there before assuming the dishwasher drain pump has failed.
Most likely: Food sludge, glass chips, labels, or grease are slowing the water at the filter and drain path. If the dishwasher hums or tries to drain but leaves water behind, a clog is more likely than a failed part.
First figure out what kind of "not draining" you have: a shallow puddle under the filter, several inches of dirty water, or a dishwasher that runs the drain cycle but sends little or nothing to the sink drain. That split matters. Reality check: a little clean water in the sump can be normal, but standing dirty water across the tub floor is not. Common wrong move: running cycle after cycle with a packed filter just turns debris into sludge and makes the clog harder to clear.
Don’t start with: Don’t start by ordering a dishwasher drain pump. Pumps do fail, but on this symptom they are not the first bet.
A small amount of water sits in the sump area, but dishes may still come out mostly clean.
Start here: Check whether it is just a small sump reservoir or actual standing water across the tub floor. If it is only a little water down in the low spot, that can be normal.
The bottom of the dishwasher is covered and the cycle ends with cloudy or smelly water left behind.
Start here: Start with the filter, sump well, and any visible debris around the pump cover before moving to the hose.
The machine sounds like it is pumping, but the water level barely drops or drains very slowly.
Start here: Check the sink-side drain path, air gap if you have one, and the dishwasher drain hose for a kink or grease plug.
The dishwasher tries to drain but sounds strained, harsh, or stuck.
Start here: Shut power off and inspect the sump for broken glass, bone fragments, labels, or other debris jamming the dishwasher drain pump impeller.
This is the most common cause when water stays in the tub after a normal cycle. Food paste, paper labels, glass chips, and grease collect right where the water has to leave.
Quick check: Remove the lower rack, pull the dishwasher filter, and look for sludge or hard debris in the sump opening.
If the dishwasher seems to pump but the water has nowhere to go, it backs up and stays in the tub. This is common after sink drain work or when the kitchen drain runs slow.
Quick check: Run the sink, check for a slow kitchen drain, and inspect the air gap cap if your sink has one.
A hose can sag, kink behind the unit, or pack with grease and debris. That gives you weak draining even when the pump is trying.
Quick check: Look under the sink for a crushed, sharply bent, or greasy dishwasher drain hose.
This moves up the list when the filter and hose are clear but the dishwasher only hums, buzzes, or drains weakly every time.
Quick check: After disconnecting power, inspect the pump area for debris. If it is clear and the pump still only hums or will not move water, the pump is suspect.
A small amount of water down in the low sump area can be normal on many dishwashers. You do not want to tear into a machine that is actually fine.
Next move: If there is no real standing water across the tub floor, you likely do not have a repair issue right now. If the tub floor is holding dirty water, move to the filter and sump check.
What to conclude: This separates normal retained sump water from an actual blocked drain path.
This is the highest-payoff first repair path. Most no-drain complaints start here, and it costs nothing but a few minutes.
Next move: If the next drain cycle clears the water normally, the blockage was at the filter or sump. If water still stands or the pump sounds strained, keep going to the sink-side and hose checks.
What to conclude: A dirty filter or blocked sump was either the whole problem or part of it. If symptoms improve but do not fully clear, there may still be a downstream restriction.
When the dishwasher can push water but the path out is restricted, it acts like a pump problem even though the real issue is outside the pump.
Next move: If the dishwasher drains after clearing the sink-side path or straightening the hose, the restriction was outside the tub. If the sink side is clear and the dishwasher still hums or leaves water, inspect the pump area next.
Sound tells you a lot here. A healthy drain pump has a steady, purposeful sound. A jammed one often hums, chatters, or buzzes without moving much water.
Next move: If removing debris changes the sound and the dishwasher drains, the pump was jammed, not failed. If the pump area is clear and the dishwasher still only hums or drains very weakly, the dishwasher drain pump is the leading suspect.
By this point you should know whether you fixed a blockage, found a bad hose, or narrowed it to the dishwasher drain pump. Finish the repair instead of guessing.
A good result: If the tub drains fully and does not refill with dirty water, the repair path was correct.
If not: If the same symptom remains after the supported checks and repair, there may be a deeper internal restriction or control issue that needs hands-on service.
What to conclude: You have moved from simple blockage checks to the most likely actual repair parts without buying blindly.
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A small amount of clean water down in the lowest sump pocket can be normal. What is not normal is dirty water spread across the tub floor or water that smells bad and covers the filter area.
Yes. If the sink drain or air gap is restricted, the dishwasher may pump against that blockage and leave water behind. That is why the sink-side path is worth checking before blaming the pump.
Suspect the dishwasher drain pump after the filter, sump, air gap, and drain hose are clear and the machine still only hums, buzzes, or fails to move water. A jammed pump can sound similar, so check for debris first.
No. Drain cleaner can damage parts, create a burn hazard, and make the next repair messier and less safe. Stick with manual cleaning, warm water, mild soap where appropriate, and physical blockage checks.
That usually points to a restriction farther down the drain path or wastewater flowing back from the sink side. Check the air gap, sink drain connection, and dishwasher drain hose routing before replacing internal parts.