You open the dishwasher after a cycle and find an inch of cloudy water sitting over the racks. The dishes look clean enough, so the wash side is working — it is the drain side that has stopped. A dishwasher that will not drain is a plumbing problem as much as an appliance problem, because the water has to travel through a filter, a pump, a flexible hose, and often a connection to the sink drain or garbage disposal before it leaves the house.
Most cases trace back to something simple: a clogged filter, a kinked hose, a blocked air gap, or a disposal fitting that has never been punched out. This guide explains the drain path, the checks to run in order, and the point at which the repair moves beyond a homeowner's toolkit.
Dirty water leaves the tub through a sump at the bottom, passes a filter screen that catches food particles, and is pushed by the drain pump into a corrugated hose behind the unit. That hose typically loops up high under the counter before connecting either to the sink's drain tailpiece, to a dedicated drain connection, or to the garbage disposal.
Two details make the difference between a dishwasher that drains properly and one that siphons dirty water back into the tub. First, the drain hose needs a high loop — a section that rises above the level of the connection before descending. Second, if an air gap fitting sits on the counter, it provides a physical break between the appliance and the drain. Both features stop wastewater from being pulled backward by gravity or by pressure changes in the sink drain.
Begin with the simplest possibility: the cycle may not have finished. Many models pause with water in the tub if the door was opened or a cycle was interrupted. Run a rinse-and-hold or a short cycle and let it complete, then listen for the drain pump at the end. If you hear the pump running but water stays put, the blockage is downstream. If you hear nothing at all, the pump or its control may be the issue.
Next, check the sink. If the kitchen sink drains slowly or gurgles while the dishwasher runs, the shared drain line is partially clogged and the dishwasher is trying to push water into a restricted pipe. That changes the repair entirely: the problem is in the sink drain, not the appliance. Our guide to kitchen drain cleaning covers how grease and food buildup slow that line down.
With the power off and the tub emptied as best you can with a sponge and towels, remove the bottom rack and take out the filter assembly. Most modern dishwashers have a cylindrical filter plus a flat screen; both twist or lift out. Rinse them in the sink and use a soft brush to clear grease film and food fibers from the mesh. Grease that cools inside the sump can coat the screen completely and stop flow.
While the filter is out, look into the sump with a flashlight for glass shards, bones, seeds, or a piece of plastic wrap wrapped around the pump impeller. Remove debris with needle-nose pliers, never with your fingers. Check that the drain pump cover, if your model has one, is seated correctly after cleaning — a cover that is not locked down will let water bypass the pump and sit in the tub.
Pull the dishwasher out far enough to reach the drain hose, or access it from the cabinet beside the unit. Look for kinks, a hose pinched behind the frame, or a loop that has dropped below the level of the connection. Disconnect the hose at the sink end over a bucket and inspect the opening; a slug of grease or a wad of food debris at the fitting is common. Flush the hose with water from a pitcher to confirm it is clear.
If the dishwasher drains into a garbage disposal, there is a specific trap to check. The disposal has a plug covering the dishwasher inlet, and it must be removed during installation. If it was never knocked out, the dishwasher has been draining into a sealed port since day one, which usually shows up as standing water from the very first cycle. Also confirm that the disposal has been run recently — a disposal full of food waste will back water up into the dishwasher immediately. Our garbage disposal care guide explains how to keep that path clear.
Connect with local plumbing professionals who can clear the drain line, fix the disposal connection, and get the cycle finishing properly.
(888)205-1556An air gap is the small chrome cylinder on the counter next to the faucet, with a plastic cap on top. Water from the dishwasher passes through it on the way to the drain, and if the internal passages clog with grease or the cap is pushed down, water backs up into the tub. Twist off the cap, lift out the inner body, and clean both parts under running water. Reassemble carefully — the parts only fit one way, and a missing washer will leak onto the counter.
If there is no air gap, the drain hose must have a high loop. Secure the hose to the underside of the counter so its highest point sits above the sink's drain connection, using a clamp or zip tie. Without that loop, dirty water from the sink can siphon back into the dishwasher, leaving a pool in the bottom and a smell that returns no matter how often you clean the filter.
Call for help if the drain hose and filter are clear but the tub still holds water, if the drain pump hums without moving water, if water leaks from under the unit, or if the sink drain and dishwasher both back up at the same time. A shared clog deep in the drain line needs augering or jetting that an appliance cannot handle, and repeated backups point to a grease problem further down the pipe.
Also call if the dishwasher connection was recently changed, if a new disposal was installed, or if the unit trips a breaker when the drain cycle starts. Those are installation and electrical issues rather than maintenance. Before anyone arrives, shut off the water supply to the sink and empty the tub so the technician can work without a flood — and if you smell sewer gas near the sink, treat it as urgent rather than waiting for a convenient appointment.
One more preventive habit: scrape plates rather than rinsing them, run the disposal before starting the dishwasher, and use a grease-free approach to kitchen cleanup so the shared drain line stays clear. Most dishwasher drain failures start as slow grease accumulation somewhere in that path, long before the water stops moving entirely.