Direct answer: If a Bosch dishwasher leaves water in the bottom, the usual cause is a blockage in the dishwasher filter, sump, drain hose, or sink-side drain path. A failed internal drain part is possible, but it is not where I would start.
Most likely: Start with the standing-water pattern: a shallow clean puddle after the cycle can be normal on some machines, but enough water to cover the filter or slosh onto dishes points to a restricted drain path.
Pull the lower rack, look at how much water is actually sitting there, and work from the tub outward. Reality check: a little water below the filter screen is often normal. Common wrong move: running cycle after cycle without clearing the filter and sump first just packs debris tighter into the drain path.
Don’t start with: Do not start by ordering a drain pump or tearing the door apart. Most of these calls end with debris in the filter well, a kinked dishwasher drain hose, or a clogged air gap or sink connection.
You see a small amount of clean water down in the sump, but dishes are mostly dry and the tub floor is not flooded.
Start here: This may be normal. Confirm the water is only in the low sump pocket and not spread across the tub floor before chasing a repair.
There is enough water to wet the flat tub floor, float scraps around, or splash when you pull the lower rack.
Start here: Go straight to the filter, sump cover, and visible drain path checks.
The water smells bad, looks cloudy, or has bits of paper label, glass, seeds, or grease in it.
Start here: Expect a blockage in the dishwasher filter, sump, or drain hose before you suspect an electrical failure.
The machine sounds like it is trying to drain, then stops, with little or no water movement at the sink side.
Start here: Check for a jam in the sump or a restriction in the dishwasher drain hose and air gap.
This is the most common reason a dishwasher leaves dirty standing water. Food scraps, broken glass, labels, and grease collect right where the machine starts draining.
Quick check: Remove the lower rack and filter, then look for sludge, seeds, glass, or hard debris in the well below.
If the tub water is fairly clean and the machine seems to try draining, the blockage is often farther down the line at the hose loop, air gap, or sink tailpiece connection.
Quick check: Look under the sink for a kinked hose, a clogged air gap, or a plugged hose nipple where the dishwasher ties into the sink drain or disposal inlet.
A slow kitchen sink or backed-up disposal can keep dishwasher water from leaving, or can let dirty sink water wash back into the tub.
Quick check: Run the kitchen sink. If it drains slowly, gurgles, or backs up, fix that drain issue before blaming the dishwasher.
Once the filter and drain path are clear, a pump problem moves up the list, especially if you hear a hum, grinding, or no real water movement during drain.
Quick check: After clearing debris, run a cancel or drain cycle and listen near the bottom front. A strong drain sounds steady and moves water fast; a weak hum with no flow points deeper.
Some dishwashers keep a little clean water down in the sump to protect seals. You do not want to chase a normal condition.
Next move: If you confirm the water is only a small amount in the low sump pocket, the dishwasher may be draining normally. If water is standing across the tub floor or leaving debris behind, move to the filter and sump inspection.
What to conclude: This separates normal retained sump water from a true not-draining complaint.
This is the highest-payoff check. Most standing-water complaints start here, and it is the least destructive thing you can do.
Next move: If the next drain cycle clears the tub normally, the blockage was at the filter or sump. If the tub still holds water, the restriction is likely farther along the drain path or the drain pump is not moving water well.
What to conclude: Dirty water with debris almost always points to this area first. If it was packed with gunk, you likely found the main problem.
A Bosch dishwasher can be perfectly fine internally and still leave water behind if the hose is kinked or the sink connection is blocked.
Next move: If water now drains fast and fully, the restriction was in the hose route or sink-side connection. If the hose and sink connection are clear but the dishwasher still leaves water, check whether the kitchen sink itself is draining properly.
A slow sink drain can hold dishwasher water back or let dirty water run back into the tub. That is not a dishwasher parts problem.
Next move: If fixing the sink drain restores normal dishwasher draining, the dishwasher itself was not the root problem. If the sink drains normally and the dishwasher path is clear, the remaining likely cause is a jammed or failing dishwasher drain pump.
Once the filter, sump, hose, air gap, and sink drain path are clear, the pump becomes the main remaining failure point.
A good result: If the dishwasher now drains fully, run one full wash and recheck the tub bottom afterward.
If not: If it still leaves water and the pump only hums or barely moves water, replace the dishwasher drain pump if you are comfortable with lower-access disassembly, or book service.
What to conclude: A clear drain path plus weak or no water movement narrows the problem to the dishwasher's drain hardware or electrical control side.
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Sometimes, yes. A small amount of clean water down in the recessed sump area can be normal. Water spread across the visible tub floor, dirty water, or water high enough to slosh around is not normal.
That usually means the dishwasher filter or sump is clogged, or the drain path is restricted enough that dirty wash water is not leaving fully. Start with the filter and sump before suspecting a part failure.
Yes. A slow or backed-up kitchen sink drain can keep dishwasher water from draining out, and in some setups it can let dirty water wash back into the dishwasher tub.
After the filter, sump, hose, air gap, and sink drain path are confirmed clear, a bad drain pump usually shows up as a hum with little water movement, weak draining, grinding, or no effective discharge during the drain cycle.
No. Drain cleaners can damage dishwasher parts and create a safety hazard when you open hoses or the sump afterward. Clear the filter, sump, hose, air gap, and sink drain mechanically instead.