Dishwasher Not Draining? Causes, Fixes & When to Call

5/13/2026

Dishwasher Not Draining? Causes, Fixes & When to Call

Why it matters: You open your dishwasher expecting clean, dry dishes, but instead, you find a pool of dirty, standing water at the bottom of the tub. A dishwasher that won't drain not only fails to clean your dishes, but it can also cause foul odors, mold growth, and eventually, expensive kitchen leaks.

While a tiny bit of water beneath the filter is normal to keep seals from drying out, standing water that covers the filter or floods the bottom of the tub is a clear sign of a drainage failure. This is one of the most common issues homeowners face with dishwashers from Samsung, Bosch, Whirlpool, LG, and GE.

Here are the 8 most common reasons your dishwasher is not draining, what you can safely check yourself, and when it’s time to call ApplianceGo for fast, same-day repair.

1. Clogged Drain Filter (Check This First!)

The most frequent cause of a dishwasher not draining is completely preventable: a clogged drain filter. Located at the bottom center of the tub, the filter traps large food particles, broken glass, labels from jars, and grease to prevent them from entering the drain pump. Over time, this debris creates a watertight seal, preventing the water from escaping.

How to Check: Remove the bottom rack. Twist the cylindrical filter counterclockwise and pull it up.
The Fix: Wash the filter in the sink under warm water with a soft brush and dish soap. Do not run the dishwasher without the filter in place.

2. Obstructed Air Gap or High Loop

If your dishwasher is connected to a sink air gap (the small chrome cylinder sitting on the back of your sink), its job is to prevent dirty sink water from back-flowing into the dishwasher. If the air gap gets clogged with debris, the dishwasher physically cannot push water out.

How to Check: Remove the chrome cover of the air gap and the plastic cap beneath it. Look for built-up gunk.
The Fix: Use a pair of tweezers or a small bottle brush to clear out the debris. If you don't have an air gap, ensure your drain hose is secured in a "high loop" under the sink, rising above the drain connection point.

3. Garbage Disposal Knockout Plug Left In

Did you just install a new garbage disposal? If your dishwasher worked fine until you replaced your disposal, the installer likely forgot to remove the "knockout plug." The disposal comes with a solid plastic plug in the dishwasher connection port. If it isn't punched out with a hammer and screwdriver before the hose is attached, the water has nowhere to go.

The Fix: Disconnect the dishwasher hose from the disposal, use a punch to knock the plastic disc into the disposal (retrieve it before running the disposal), and reattach the hose.

4. Clogged or Kinked Drain Hose

The drain hose carries the dirty water from the drain pump to your sink or disposal. If the hose is kinked behind the machine (often happening when the machine is pushed too far back during installation) or clogged with grease and food sludge, the water will back up into the tub.

How to Check: Inspect the ribbed plastic hose under your sink for severe bends. A clog usually forms where the hose connects to the disposal or sink plumbing.
The Fix: Professional Repair Recommended. A technician can pull the unit out, clear the obstruction, or replace a damaged hose.

5. Failed or Blocked Drain Pump

The drain pump uses a small impeller to force water out of the machine and through the hose. If a piece of hard debris—like a popcorn kernel, a shard of glass, or a pistachio shell—makes it past the filter, it can physically jam the impeller blades. Alternatively, the electrical motor within the pump can simply burn out due to age or overheating.

How to Check: Listen closely when the dishwasher is supposed to be draining. If you hear a low humming or buzzing sound but no water is moving, the pump is likely jammed. If you hear nothing at all, the motor may be dead.
The Fix: Professional Repair Required. A technician will need to access the pump underneath the machine, remove the blockage, or replace the entire drain pump assembly if the motor has failed.

6. Faulty Check Valve

The check valve is a small rubber flapper located near the drain pump outlet. It allows water to flow out of the dishwasher but snaps shut to prevent dirty water from flowing back in. If the rubber degrades, gets stuck open, or gets jammed with debris, the drained water will simply flow right back into the tub after the pump shuts off.

The Fix: Professional Repair Required. A technician must inspect the valve and replace it if the rubber is warped or torn.

7. Clogged Sink Drain

Sometimes, the dishwasher is working perfectly, but the household plumbing is the problem. Because the dishwasher drains into the same pipe as your kitchen sink, a clog in the sink's P-trap or the main branch line will cause water to back up into the dishwasher.

How to Check: Turn on your kitchen faucet. Does the sink drain slowly or back up? If so, the plumbing is the issue.
The Fix: Clear the sink clog using a plunger, by cleaning the P-trap, or by calling a plumber.

8. Defective Control Board

The main electronic control board acts as the "brain" of the dishwasher, sending voltage to the drain pump when it's time to empty the tub. If a relay on the board shorts out or burns up, the board will never send the signal (or the power) to the pump.

The Fix: Professional Repair Required. A technician will use a multimeter to verify if voltage is reaching the pump. If the pump is good but receives no power, the control board must be replaced.

When to Call ApplianceGo for Dishwasher Repair

While clearing the filter or cleaning an air gap are easy DIY fixes, accessing the drain pump, check valve, or electronic control board requires removing the unit from the cabinetry and handling complex electrical and plumbing connections.

You should call ApplianceGo if:

You have cleaned the filter and the air gap, but the water still won't drain.
You hear a loud buzzing or grinding noise when the machine tries to drain (indicating a jammed pump).
The dishwasher stops mid-cycle and displays an error code.
You suspect a broken drain pump or a failed control board.

ApplianceGo provides same-day, expert dishwasher repair across New York, New Jersey, and Connecticut. Our licensed technicians carry factory-certified drain pumps, hoses, and check valves for all major brands—allowing us to fix the drainage issue and get your kitchen back to normal on the very first visit.

Call (929) 720-6200 or book your service online to get your dishwasher draining perfectly again today!