Direct answer: A dishwasher that is not draining completely usually has a partial blockage in the filter, sump, drain hose, sink air gap, or sink-side connection. A bad drain pump is possible, but it is not the first thing to assume.
Most likely: Start with the standing water pattern: a little clean water can be normal, but murky water, food bits, or water rising higher after the cycle usually means the drain path is restricted.
If there is an inch or two of water left in the tub, work from the inside out. Check the filter and sump first, then the hose path to the sink or air gap, then listen for what the pump is doing. That order saves the most time and avoids tearing into the machine for a blockage that is sitting in plain sight.
Don’t start with: Do not start by ordering a dishwasher drain pump just because you hear humming. A clogged filter or hose causes that all the time.
A small amount of clean water sits below the filter area, but dishes are otherwise clean and the level does not rise.
Start here: Confirm whether the water is actually above the filter screen or just in the low sump area. A little clean water can be normal on some machines.
Murky water, food bits, or grease remain in the bottom after the cycle ends.
Start here: Start with the dishwasher filter and sump cleanup. That is the most common cause.
Water level drops partway, then stops, or the problem comes and goes.
Start here: Check for a kinked dishwasher drain hose, a clogged sink air gap, or buildup where the hose connects under the sink.
The machine tries to drain, but the sound is strained, weak, or rough.
Start here: Clear the filter and sump first. If the drain path is clear and the pump still only hums, the dishwasher drain pump moves higher on the list.
This is the most common reason for partial draining. Food scraps, labels, glass bits, and grease slow the water enough that some stays behind.
Quick check: Remove the lower rack, take out the filter if your model has one, and look for sludge or debris around the sump opening.
A partial clog in the hose or where it ties into the sink drain lets some water out but not enough to finish the job.
Quick check: Look under the sink for a kinked hose, a low sag, or buildup at the hose connection or air gap.
If your sink has a small air gap fitting near the faucet, it can clog with food and force water back into the dishwasher.
Quick check: Remove the air gap cap and check for sludge or debris inside.
If the drain path is clear and the pump only hums, trips, or barely moves water, the pump may be worn or jammed.
Quick check: Listen during the drain portion. A strong pump has a steady moving-water sound. A weak hum with little flow points deeper.
Some dishwashers keep a small amount of clean water in the sump by design. You do not want to chase a problem that is not there.
Next move: If you confirm there is only a small clean amount in the sump, you may not need a repair. If there is standing dirty water or the level is clearly too high, move to the filter and sump check next.
What to conclude: This separates normal retained sump water from an actual partial blockage or pump problem.
This is the highest-probability fix and the least destructive place to start. Partial drain complaints often end here.
Next move: Reassemble, restore power, run a short rinse or cancel-drain, and see whether the tub clears normally. If water still drains slowly or only partly, the restriction is likely farther along the drain path.
What to conclude: A dirty filter or blocked sump was the problem if draining improves right away. If not, the hose path or pump needs attention.
A dishwasher can act like it has a bad pump when the real problem is under the sink. This is especially common when the sink drains slowly too.
Next move: Run a drain cycle again. If water now leaves quickly, the blockage was in the hose route, air gap, or sink-side connection. If the hose route is clear and the sink-side connection is open, the next question is whether the pump is actually moving water.
Sound tells you a lot here. A strong pump with poor flow usually means blockage. A weak hum or rough grinding after the path is clear points more toward the pump itself.
Next move: If the sound and flow now seem normal after cleaning, keep using the dishwasher and verify over the next few cycles. If the drain path is clear and the pump still hums, stalls, or grinds, plan for a pump inspection or replacement.
Once you know whether the problem is blockage or a weak pump, the next move is straightforward. The common wrong move is replacing parts while the hose or air gap is still clogged.
A good result: You have matched the fix to the actual failure instead of guessing.
If not: If a clear drain path and a new pump still do not solve it, stop there and have the dishwasher professionally diagnosed for wiring, control, or internal mechanical issues.
What to conclude: You should now have either a confirmed blockage fix, a supported hose replacement, or a supported pump replacement decision.
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A small amount of clean water in the recessed sump area can be normal on some dishwashers. If the water is dirty, above the filter area, smells bad, or leaves food behind, that is not normal and usually points to a blockage.
Yes. If the sink drain or the dishwasher connection under the sink is restricted, the dishwasher may only drain partway or may back dirty water into the tub. If the kitchen sink is slow too, deal with that sink-side restriction along with the dishwasher checks.
Not as a first move for standing water. Start by cleaning the dishwasher filter, sump, air gap, and hose path by hand. That is safer and more effective for real blockages. Do not mix cleaners or pour harsh drain chemicals into the dishwasher.
Suspect the dishwasher drain pump after the filter, sump, hose path, and air gap are clear. If the pump only hums, grinds, or barely moves water with a clear drain path, the pump becomes a much stronger suspect.
A very common cause is the disposal inlet knockout plug not being removed where the dishwasher drain hose connects. If that plug is still in place, the dishwasher cannot drain properly even though the rest of the machine is fine.
Not for long. Standing dirty water can smell, redeposit debris on dishes, and strain the pump. Fix the blockage or confirmed pump issue before regular use.