Direct answer: If your LG dishwasher leaves water in the bottom, the usual cause is a blockage in the filter, sump, drain hose, air gap, or sink drain connection. A drain pump is possible, but it is not where I’d start.
Most likely: Start with the standing-water pattern: a shallow clean puddle after the cycle often points to a partial drain restriction, while a tub full of dirty water usually means the drain path is badly blocked or the dishwasher never pumped out.
Pull the lower rack, look at the water level, and check whether the dishwasher sounds like it tries to drain. That separates a simple clog from a pump problem fast. Reality check: a little dampness around the sump is normal, but visible standing water across the tub floor is not. Common wrong move: running cycle after cycle with dirty water still in the base just packs debris tighter into the drain path.
Don’t start with: Don’t start by ordering a dishwasher drain pump. Most of these calls turn out to be food debris, glass, grease sludge, or a kinked hose.
A thin puddle or low ring of fairly clean water is left after the cycle, but dishes may still come out mostly clean.
Start here: Start with the filter assembly, sump opening, and drain hose for a partial restriction.
Food bits or cloudy water are sitting in the bottom and the dishwasher clearly did not empty.
Start here: Check for a blocked filter, clogged sump, plugged air gap, or a sink drain connection packed with sludge.
The machine sounds like it is trying to pump out, but the water level barely changes.
Start here: Look for debris in the sump or a blockage in the dishwasher drain hose before suspecting the dishwasher drain pump.
The cycle finishes with water left behind, but you never hear the usual pump-out sound.
Start here: Make sure the cycle actually completed, then check for a stuck float issue or a failed drain pump if the drain path is clear.
This is the most common reason for standing water. Food scraps, labels, broken glass, and grease collect right where the water has to leave the tub.
Quick check: Remove the lower rack and filter pieces. If you find sludge, seeds, paper, or glass around the sump opening, clean that out first.
A partial clog lets some water out but leaves a puddle behind. A hard kink or heavy clog leaves a lot more water in the tub.
Quick check: Follow the dishwasher drain hose as far as you can under the sink. Look for a sharp bend, crushed section, or greasy buildup at the sink connection.
If the dishwasher drains into an air gap or a branch tailpiece on the sink drain, that connection can clog and back water into the dishwasher.
Quick check: If you have an air gap on the sink, pop the cap and look for debris. If there is no air gap, disconnect the hose at the sink-side fitting and check for blockage there.
When the drain path is clear but the dishwasher only hums, drains weakly, or does not pump at all, the pump becomes the likely suspect.
Quick check: After clearing the filter and hose path, run a drain cycle. If the pump only hums or moves very little water, the dishwasher drain pump may be jammed or worn out.
A dishwasher can keep a small amount of water down in the sump area. You are looking for water spread across the tub floor or high enough to touch the filter area.
Next move: If there is no real standing water, you likely do not have a drain failure. If water is clearly left in the tub, move on to the filter and sump check.
What to conclude: This keeps you from chasing a problem that is really just normal retained sump water.
This is the highest-payoff check. Most dishwashers that leave water behind have debris right at the filter or sump.
Next move: If the next drain cycle clears the tub normally, the blockage was at the filter or sump. If water still remains, the restriction is likely farther along the drain path or the pump is not moving water well.
What to conclude: A clean filter and sump rule out the most common easy fix and make the next checks more meaningful.
A dishwasher can have a perfectly good pump and still leave water behind if the hose or sink connection is restricted.
Next move: If the dishwasher drains normally after clearing the sink-side path, the problem was outside the tub. If the hose path is clear and the dishwasher still leaves water, listen closely to the pump behavior in the next step.
Sound and water movement tell you a lot. A strong drain pump has a distinct push of water. A jammed or failing one often hums, buzzes, or stays unusually quiet.
Next move: If you hear a strong pump-out and see good flow, recheck for a partial blockage you may have missed in the hose or sink connection. If the pump hums with little flow or stays silent while water remains, the dishwasher drain pump is the leading suspect.
By this point you should know whether you had a blockage, a hose issue, or a likely pump failure.
A good result: If the tub finishes empty except for normal sump moisture, the repair path was correct.
If not: If water still returns after these checks, you are past the simple homeowner fixes and need a closer internal diagnosis.
What to conclude: You have narrowed the problem to a confirmed clog cleanup, a hose replacement, or a likely drain pump failure.
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A small amount of water down in the sump pocket can be normal. Water spread across the tub floor or around the filter after the cycle is not and usually points to a clog or weak drain pump.
Yes. If the dishwasher drains into an air gap or a sink drain connection that is packed with grease and sludge, the dishwasher can back up and leave water in the tub.
If the filter, sump, hose, and sink-side connection are clear but the dishwasher only hums, drains weakly, or makes no real pump-out sound, the drain pump becomes much more likely.
No. Drain cleaners can damage dishwasher parts and seals, and they create a nasty safety problem when you open hoses later. Clean the filter and hose path mechanically instead.
That usually means a partial restriction. The pump can push some water through, but grease, food debris, or a kinked hose slows the flow enough that water is left behind at the end of the cycle.