Dishwasher Not Draining? Solid Causes and DIY Fixes

How the drain system works

At the end of every cycle, a dishwasher runs a drain phase. The drain pump, typically a small impeller driven by an electric motor at the bottom of the tub, pulls water out through a strainer basket, pushes it up a drain hose, and sends it either into the sink drain through an air gap or into a disposer connection. If any part of that path is blocked, the water has nowhere to go and sits in the tub.

The good news: the system has only a handful of failure points, and most are accessible from inside the tub without removing the dishwasher from under the counter. The parts that wear out, like the pump motor or the check valve, are usually behind a removable panel at the front or bottom and can be inspected with basic tools. This article covers the three causes that account for most standing-water cases: a clogged filter, a blocked or kinked drain hose, and drain pump failure.

Before you start, turn off power at the circuit breaker. Water and electricity do not mix. Also, keep a towel and a shallow pan nearby, because even a pumped-down dishwasher holds some water in the sump area.

Clogged filter and drain basket

The filter is the first and most common culprit. Modern dishwashers recirculate water throughout the cycle, passing it through a fine mesh filter to catch food particles. Over time, those particles pack into the mesh, and the water level sensor may not read correctly, or the pump may not get enough water to push out the drain. Many dishwasher not draining incidents are just a filter that looks clean on top but has a layer of sludge underneath.

To check the filter, pull out the bottom rack and remove the cylindrical filter assembly in the corner of the tub. Most turn counterclockwise and lift out. Rinse it under running water and use a soft brush to clear the fine mesh. Look into the sump opening below for debris like a fragment of a glass or a broken toothpick. A clogged filter is the easiest fix and the one most likely to solve the problem. For a full walkthrough, see our dishwasher filter cleaning guide.

If the filter is clean, the next spot is the drain basket or sump area, where a small grate sits below the filter. If anything blocks it, water will sit in the tub. Remove obvious debris. A turkey baster or wet/dry vacuum can help pull out accumulated water so you can see the bottom clearly.

• Turn off the dishwasher and wait for the motor to stop.
• Pull the bottom rack out to access the filter at the rear or corner.
• Twist the filter counterclockwise and lift it out.
• Rinse the filter under running water; use a toothbrush for the mesh.
• Inspect the sump opening below for broken glass, seeds, or other debris.

Drain hose blocked or kinked

If the filter and sump are clear, the blockage may be further downstream in the drain hose. The hose runs from the pump outlet up to the sink drain or disposer connection. It can be pinched under the cabinet, blocked with grease, or clogged at the point where it connects to the sink drain. Over time, hard water deposits and food residue can build up inside the hose and reduce its diameter enough to leave water standing.

Check the hose visually along its accessible run under the sink. Look for a sharp bend or a spot where the hose is compressed against the cabinet wall. A kink can happen during installation, especially with portable dishwashers that get moved in and out. If you find one, reposition the hose so it has a smooth curve. The hose should also loop up high before dropping into the drain connection to prevent backflow, as covered in our drain hose high-loop article.

To clear a clog inside the hose, disconnect it at both ends. On one end, the hose attaches to the pump outlet, and on the other, it connects to the sink drain or disposer. Use a long, flexible brush or a wire coat hanger with a hook to pull out debris. Run water through the hose from one end to the other to confirm it flows freely. Avoid using chemical drain cleaners, they will not reach the clog and can damage rubber seals and pumps.

If the water drains into a sink drain through an air gap device mounted on the countertop, pop the cap off and inspect the small hose inside. Air gaps clog more often than people expect and are a very common cause of standing water. See our air gap cleaning guide for the details.

Drain pump failure or a stuck impeller

When the filter, sump, hose, and air gap are all clear, the remaining suspect is the drain pump itself. The pump has a small impeller that spins to push water out. It can fail in one of two ways: a piece of debris can jam the impeller so it cannot spin, or the motor can burn out. A jammed impeller is a simpler fix, you can often clear it in a few minutes by reaching into the pump inlet, though the impeller sits at the bottom and may require removing the pump assembly.

A clear symptom of a jammed impeller is a humming sound at the drain phase with no water moving. If you hear a hum but the tub stays full, the pump motor is getting power but the impeller is stuck or the motor is burned out. Shut off the dishwasher, then access the pump from underneath or from the front panel. On many models, the pump assembly is behind a removable kickplate and held by a few screws and a wiring connector.

Inspect the impeller, look for a coin, a broken glass shard, or a wad of food debris caught between the vanes. Clear it and spin the impeller by hand to confirm it rotates freely. If the impeller spins but the pump still does not drain, the motor winding may be burned out. A multimeter can check the motor for continuity, but if you are not comfortable working with electrical parts, this is the point at which to call a repair technician. For a detailed procedure, see our drain pump cleaning guide and the drain pump replacement guide.

• Humming at the drain phase with no water moving
• Impeller jammed with a coin, glass, or food debris
• Burned-out motor winding (no continuity on the multimeter)
• Failed drain pump check valve, allowing water to flow back

Check valve and other plumbing issues

Some dishwashers have a small check valve or a duckbill valve inside the drain pump outlet. That valve keeps water from flowing back into the tub after the cycle. If it fails or sticks, water can leak back, leaving a shallow puddle even though the pump ran. The valve is a small rubber or plastic flap that opens when the pump pushes water and closes when the pump stops. It rarely, if ever, needs replacement, but it can be checked when you have the pump open.

Less common but still possible: the drain line to the sink is clogged past the point where the dishwasher hose connects. If you run the sink and see water backing up in the drain, the problem is likely in the sink plumbing, not in the dishwasher. This is worth verifying before you open the dishwasher pump.

If the dishwasher installs with a high loop but water still backs up, review the dishwasher drain options article for a comparison of air gap, high loop, and disposer connections. A misconfigured connection is a common cause of recurring drainage complaints.

Prevent future blockages

Once the tub is empty and the cycle runs clean, a few habits keep it that way. Scrape dishes well, but skip rinsing, ENERGY STAR notes that rinsing before loading increases both water and energy use, and that today's dishwashers and detergents are designed to do the cleaning without it. Run the dishwasher regularly, a machine that sits unused for weeks can develop dried-on grime in the sump. And clean the filter monthly, or at least every few months, to catch debris before it builds up.

If hard water is a factor in your area, scale can build up inside the drain path over time. Periodic cleaning with citric acid can help keep the internal hoses and sump clear. See our guide on descaling with citric acid for a safe procedure. Also check the drain hose cleaning guide for a deeper clean.

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Questions

How often should I clean my dishwasher filter to prevent drain issues?

At least once a month if you run the dishwasher daily. A clogged filter is the most common cause of standing water. Monthly cleaning also keeps the drain pump and hose free of debris. If you notice a slow drain or a musty smell, clean the filter first.

Can a dishwasher drain with a partially clogged filter?

It might, but the water level can rise higher than normal because the pump has to work harder and the water flow is reduced. Over time, a partial clog will trap food particles and can lead to a full blockage. If the water level in the tub looks higher than usual during a cycle, the filter likely needs cleaning.

What should I do if my dishwasher hums but does not drain?

Turn off the machine and check the filter and sump for debris that may have jammed the pump impeller. If the filter is clear, access the pump from below and inspect the impeller for a coin or glass shard. If the impeller spins freely and the pump still does not push water, the motor may be burned out and needs replacement.

What is the most common cause of standing water in a dishwasher?

A clogged filter or a blocked drain basket, both are food debris that accumulates over time. These two together likely cause more than half of all standing-water reports. The fix takes minutes and requires no tools.

Is it normal to have a little water at the bottom of the dishwasher?

A small amount of clear water may remain in the sump or the bottom of the tub after a cycle, often because a dishwasher retains some water to keep seals moist. This is usually a few cups, not a full tub. If the water is dirty and the tub is nearly full, you have a drain problem.

Can a kinked drain hose cause a dishwasher to stop draining?

Yes. A kink or a pinch in the drain hose blocks the flow of water and can leave the tub full. This happens most commonly when a dishwasher is installed incorrectly or when a portable model is pushed back into place and traps the hose. Inspect the hose under the sink and behind the unit.

Why does my dishwasher drain slowly even though the filter is clean?

A slow drain usually points to a partial blockage farther down the line, in the drain hose, the air gap, or the sink drain connection. Check the air gap cap for debris, inspect the hose for kinks, and then disconnect the hose to clear any buildup. If the problem persists, the drain pump may be losing efficiency.