A little water sitting in the bottom of the dishwasher when the cycle ends is not automatically a problem. Most machines, Bosch, Samsung, LG, Whirlpool, GE, all of them, leave a thin film in the sump on purpose so the pump seals don’t dry out. A shallow, clear layer that doesn’t smell and doesn’t grow cycle to cycle is doing exactly what it should.
What’s not normal: visible standing water in the tub, a stale smell, or a level that creeps up a little more each time you run it. That’s a machine not finishing its drain. Here’s what’s behind it.
Normal residue vs a real problem
A working dishwasher leaves roughly a cup of water or less in the recessed sump around the filter. If you can see the tub floor clearly and there’s just a sheen down in the well, you’re fine. If the water covers the drain cover or pools across the floor of the tub, keep reading.
Why the last inch won’t leave
A sagging drain-hose loop. The drain hose is supposed to run up high near the top of the cabinet before it drops to the sink connection. That high loop stops water from siphoning back in after the cycle and blocks sink-side gunk from washing back into the tub. Let the loop droop and the machine drains fine, then gets water pushed back the moment the sink runs.
A partly clogged filter. Food, a soaked paper label, a stray toothpick, or bits of glass can choke the screen without stopping it cold. Most of the water goes, the last inch backs up. The cylindrical filter twists out by hand, and this is the first thing to check.
Knockout plug still in the disposal. Only in play if a disposal went in recently. There’s a plastic plug in the disposal’s dishwasher inlet that has to come out during install. Miss it and the dishwasher drains into a dead end.
A slow restriction at the drain connection. The hose ties into either the disposal or a sink-deck air gap. Grease and soap scum build up over months and narrow the path, so water passes but not fast enough to clear before the cycle times out.
A pump running at half strength. Filter clean and hose routed right, but the pump itself is tired. This shows up as drainage that gets a little worse over weeks, sometimes with a hum or grind at the end while water barely moves. A lodged bit of debris or a worn impeller cuts flow without killing it. Reaching it means disassembly.
Control-board or timing fault. A bad board can cut the drain step short or fire the drain relay erratically. Less common than the mechanical causes, but it happens, mostly on older machines.
How we run it down
On a partial-drain call we start the drain cycle by hand, most machines let you, and just watch. Does the pump spin up, does the level drop, where does it stall? From there: pull and read the filter, check the hose loop, test for back-siphon, and if it’s still holding water, check the pump directly. Some brands log a drain fault code, which speeds things up. Plenty don’t, because the machine technically finished, just not all the way.
Two checks worth doing first
Clean the filter. Twist it out, rinse under warm water with a soft brush, put it back. That alone clears a good share of these calls. Then eyeball the drain hose: it should loop up high behind the machine before dropping to the connection, not run flat across. Both cost nothing and are worth doing before you call anyone.
Where to draw the line
Filter clean, hose right, still standing water every cycle? You’re past the easy fixes. Getting to the pump means pulling the machine out, taking off the lower spray arm, and opening the pump area from under the tub. Beyond the effort, it’s easy to crack a hose fitting or pinch the door gasket on reassembly and turn a drain problem into a leak. Same call if the water smells sour, which means it’s sitting long enough to grow bacteria that transfers onto your dishes.
We cover dishwasher repair across the whole Bay Area, everyday brands first, often same or next day when we can. Book a visit with Bay Area Appliance Repair Service at (925) 999-4095 or online. It’s a $75 diagnostic, credited to the repair, and we’ll tell you straight whether it needs a part or just a cleaning.