Water left in the bottom of a dishwasher almost always means something between the tub and your drain is blocked — most often the filter, the drain hose, or a garbage-disposal knockout plug.
A dishwasher pumps water out through a filter, a drain hose, and into your sink drain or garbage disposal. A blockage anywhere along that path leaves standing water at the bottom of the tub. Work from the easiest, most common cause to the hardest.
Check these in order. The first accounts for most cases.
Food debris and grease cake the cylindrical filter under the lower spray arm. A blocked filter is the single most common reason water won't drain.
If a new garbage disposal was installed and the dishwasher line connects to it, a plastic knockout plug may still be blocking the connection — a very common cause right after a disposal install.
The hose from the dishwasher to the sink/disposal can kink behind the unit or clog with grease, restricting flow.
A clogged air gap on the countertop, or a drain pump with a jammed/broken impeller, will prevent draining even when everything else is clear.
Follow these in order. Stop as soon as the problem clears.
Tap Cancel/Drain (or start then cancel a cycle) — many models run a 1–2 minute drain. If water clears, you only had a stuck cycle.
Pull out the lower rack, twist out the cylindrical filter, rinse it under hot water, and clear the well underneath of food and glass. Reinstall.
If a disposal was recently installed, look under the sink, disconnect the dishwasher hose at the disposal inlet, and confirm the knockout plug was removed.
Straighten any kink in the hose. Pop the air-gap cover on the counter and clear any debris. Disconnect the hose and flush it if water still won't move.
If filter, hose, and air gap are clear, the drain pump impeller may be jammed or broken. Listen for a humming pump with no drainage — that points to pump replacement.