How Do You Fix a Dishwasher That Won’t Fully Drain?

You open the dishwasher at the end of a cycle and find standing water pooling at the bottom of the tub. Sometimes it is a shallow puddle. Other times the entire base is submerged. Either way, that water should not be there, and it is telling you something specific about where the drainage system has broken down.

Before diving into causes, here is a quick clarification that saves a lot of unnecessary troubleshoting. A small amount of water, roughly half a cup to one cup, sitting at the very bottom of the tub after a completed cycle is completely normal on most dishwasher models.

That residual water intentionally remains to keep the door gasket from drying out. Anything beyond that, visible pooling around the filter, water covering the tub floor, or water that you can hear sloshing when you move the machine, is a genuine drainage problem worth fixing.

Quick Diagnosis for a Dishwasher Not Draining Completely

What You Notice	Most Likely Cause
Water pooling around the filter area	Clogged filter blocking the sump outlet
Water present after every cycle	Blocked drain hose or kinked hose
Water drains then returns to tub	Faulty check valve or drain hose too low
New dishwasher or disposal, no drainage	Garbage disposal knockout plug not removed
Water drains slowly rather than completely	Partial filter or drain hose blockage
Gurgling sound with incomplete drainage	Air gap clogged or drain hose too deep in standpipe

What Causes Water to Stay in a Dishwasher Bottom?

Your dishwasher may fail to drain completely due to these issues:

1. The Filter and Sump Are Clogged

This is the single most common cause of standing water in a dishwasher and the first thing every technician checks before touching anything else.

The filter sits at the bottom of the tub and catches food particles, grease, and debris to prevent them from reaching and damaging the drain pump. When the filter gets packed with buildup, water cannot push through it quickly enough during the drain phase and backs up into the tub. The machine completes its cycle with water still standing because drainage was too slow or completely blocked at the filter level.

Food labels that wash off containers, coffee grounds, fibrous vegetable matter, and grease are the worst offenders. They compact into the filter mesh and create a near-solid barrier that water cannot penetrate at all.

How to Clean the Filter and Sump

Turn off the dishwasher and remove the bottom rack. Locate the cylindrical filter assembly beneath the lower spray arm. Twist it counterclockwise and lift it straight out. Separate the mesh filter from its housing if your model uses a two-piece design.

Rinse both pieces under warm running water and scrub with a soft brush to remove compacted grease and debris. The OXO Good Grips Bottle Brush (View on Amazon) cleans inside the cylindrical housing without damaging the mesh. Also, wipe the sump area beneath the filter housing with a damp cloth to clear any debris that settled there. Reinstall the filter firmly and run a short cycle to confirm complete drainage. Clean this filter every two to four weeks without exception.

2. The Drain Hose Is Kinked or Clogged

The drain hose carries dirty water from the dishwasher tub out to the sink drain or garbage disposal. When it develops a kink, gets compressed against the cabinet wall, or accumulates an internal clog from grease and debris, water cannot exit the machine regardless of how hard the drain pump works.

A kinked hose is particularly common when the dishwasher has been pushed back against the wall more forcefully than usual or when a cabinet modification has shifted the hose position without anyone noticing.

How to Inspect and Clear the Drain Hose

Pull the dishwasher forward slightly and trace the drain hose along its full length from the pump outlet to where it connects under the sink. Look for any sharp bends, kinks, or sections that are compressed against the cabinet or floor.

Straighten any kinks you find and reposition the hose so it runs smoothly without tight bends. Then disconnect both ends of the hose and flush water through it from one end to confirm it is clear internally. Use a flexible bottle brush to clear any internal blockage if water does not flow freely through the hose. If the hose is cracked, brittle, or will not hold its shape after straightening, replacement is the correct fix.

The Eastman Dishwasher Drain Hose (View on Amazon) is a durable universal replacement that fits most major dishwasher brands and comes long enough for various under-sink configurations.

3. The Garbage Disposal Is Clogged or the Knockout Plug Was Never Removed

If your dishwasher drains through the garbage disposal, a full or clogged disposal prevents the dishwasher from draining effectively. The water tries to exit into the disposal and simply has nowhere to go if the disposal itself is backed up.

Additionally, if you recently installed a new garbage disposal or a new dishwasher, there is a critically important step that gets missed surprisingly often: the knockout plug inside the disposal’s dishwasher inlet port must be removed before connecting the dishwasher drain hose. If this plug was never knocked out during installation, the dishwasher drain hose is physically blocked from day one and no amount of troubleshooting the dishwasher itself will fix the drainage problem.

How to Fix a Disposal-Related Drainage Issue

First, run the garbage disposal with cold water for 30 seconds to clear any food backup in the disposal itself. Then try running a drain cycle on the dishwasher to see if drainage improves.

If the dishwasher or disposal is newly installed, disconnect the drain hose from the disposal inlet and look inside the inlet port with a flashlight. A solid plastic plug sitting inside the port is the knockout plug that was never removed. Use a screwdriver and hammer to knock it into the disposal body, then retrieve it from inside the disposal before reconnecting the hose.

4. The Air Gap Is Blocked

Not every home has an air gap, but if yours does, a blocked air gap is a common and frequently overlooked cause of incomplete dishwasher drainage.

The air gap is a small cylindrical fitting mounted on the countertop or sink deck near the faucet. Its job is to prevent dirty sink water from siphoning back into the dishwasher. When debris accumulates inside it, it restricts the flow of water from the dishwasher drain hose and causes water to back up into the tub instead of exiting cleanly.

A gurgling sound during the drain phase is the clearest sign that the air gap is involved.

How to Clean the Air Gap

Locate the air gap on your countertop and unscrew or pop off its decorative cap. Remove the inner plastic cap below it. Use a small brush or damp cloth to clean out any debris, grease, or mineral buildup from inside both the cap and the air gap body.

Reconnect the cap firmly and run a drain cycle to confirm the gurgling stops and drainage completes fully. Clean the air gap every three to six months as part of routine maintenance. If cleaning does not restore full flow, the air gap body itself may be cracked or warped and needs full replacement, which is a straightforward and inexpensive part.

5. The Check Valve Is Stuck or Failing

The check valve is a small one-way flap or ball valve that sits in the drain system and prevents water that has already drained from flowing back into the tub. When it works correctly, you never think about it. When it fails in the closed position, it blocks drainage. And when it fails in the open position, water drains during the cycle but flows back into the tub once the pump stops.

This second failure mode is particularly recognizable: you run the dishwasher, drainage sounds normal during the cycle, but when you open the door afterward a shallow pool of water has reappeared even though it was not there mid-cycle.

How to Inspect and Replace the Check Valve

Unplug the dishwasher and access the drain pump housing. The check valve typically sits at the pump outlet or where the drain hose connects to the pump. Remove the valve and inspect it for debris, warping, or a flap that has become permanently deformed.

Clean any debris from the valve seat and flap. If the flap does not spring back to its closed position freely after being opened, the valve needs replacement. Search your model number alongside “check valve” on Amazon to find the correct part. On most machines this is a small, inexpensive component under $15 and the swap takes under 30 minutes.

6. The Drain Pump Has Failed or Is Jammed

When the filter is clean, the hose is clear, the disposal is working, and drainage still does not complete, the drain pump itself becomes the primary mechanical suspect.

The drain pump is what physically forces water out of the tub and through the drain hose during the drain phase. When the pump motor fails, its impeller jams on a foreign object like a broken glass chip, bone fragment, or seed, or the pump simply wears out from age, drainage stops entirely regardless of everything else in the system working correctly.

A drain pump that is jammed rather than failed often produces a loud humming or grinding noise during the drain phase rather than the normal quiet rushing sound of water moving through the hose.

How to Diagnose and Fix the Drain Pump

Unplug the dishwasher and manually remove any standing water from the tub using a cup and towels. Access the pump from the bottom of the tub by removing the filter assembly and reaching into the sump area below. Check whether the impeller spins freely by hand. Resistance or grinding indicates a foreign object jammed in the impeller.

Use needle-nose pliers to carefully remove any debris from around the impeller blades. If the impeller spins freely but the pump still produces no drainage during a cycle, test the pump motor with a multimeter for continuity. A failed motor needs full pump replacement (View on Amazon).

7. The Drain Hose Is Installed at the Wrong Height

This is one of the most underdiagnosed causes of incomplete dishwasher drainage and the one that is most likely to be missed entirely because the machine itself is perfectly functional.

The drain hose must loop up to a high point under the sink before connecting to the drain or disposal. This high loop prevents dirty sink water from siphoning back into the dishwasher tub through gravity. When the hose runs flat or downward without that high loop, water from the sink drain can flow back into the tub after each cycle, and the dishwasher can also experience ongoing drainage resistance from the lack of proper siphon prevention.

Similarly, if the drain hose connects to the sink standpipe and sits too far down inside it, a siphoning effect develops that actively pulls water back into the tub after the pump stops running.

How to Correct Drain Hose Height

Pull the dishwasher forward slightly and trace the drain hose under the sink. Confirm the hose forms a high loop that rises to countertop level before descending to the connection point at the disposal or drain. Secure the high loop using a hose clip mounted to the underside of the countertop or cabinet wall.

If the hose connects to a standpipe, confirm it enters the standpipe no deeper than six to eight inches. Secure it at this height with a hose clip if it keeps sliding deeper. These two corrections resolve the water-returning-after-drainage pattern immediately and require no parts beyond a zip tie or small hose clip.

Dishwasher Drainage Failure Fix Cost and Difficulty Overview

Cause	DIY Difficulty	Part Cost	Pro Repair Cost
Clean filter and sump	Very easy	Free	$80 – $130
Remove garbage disposal knockout plug	Easy	Free	$80 – $130
Straighten kinked drain hose	Easy	Free	$80 – $130
Clean air gap	Easy	Free	$80 – $130
Correct drain hose height	Easy	Free – $5	$80 – $130
Replace drain hose	Easy	$10 – $25	$100 – $175
Clear or replace check valve	Moderate	$8 – $20	$100 – $180
Clear jammed pump impeller	Moderate	Free	$100 – $180
Replace drain pump	Moderate	$25 – $65	$150 – $300

Frequently Asked Questions

How much standing water in a dishwasher is normal after a cycle?

Up to one cup of water remaining at the very bottom of the tub after a completed cycle is completely normal and intentional on most dishwasher models. It keeps the door gasket from drying out between uses. Anything beyond that, visible pooling around the filter, water covering the tub floor, or water that you can see and hear sloshing, indicates a genuine drainage problem that needs addressing.

Why does my dishwasher drain during the cycle but still have water at the end?

Water that drains during the cycle but reappears by the time you open the door almost always points to either a failed check valve allowing water to flow back from the drain hose, or a drain hose that sits too low and allows siphoning from the sink drain. Both cause water to re-enter the tub after the pump stops running rather than the drainage process failing outright.

Can a clogged garbage disposal cause dishwasher drainage problems?

Yes, directly. If your dishwasher drains through the garbage disposal, any backup or blockage in the disposal prevents the dishwasher drain water from exiting the hose. Running the disposal for 30 seconds with cold water before starting a dishwasher cycle is a simple habit that prevents this overlap from causing drainage issues.

Why is my brand new dishwasher not draining at all?

A brand new dishwasher with no drainage almost always has the garbage disposal knockout plug still in place. This plug must be physically removed from the disposal’s dishwasher inlet port during installation before the drain hose is connected. If it was overlooked during installation, the drain hose is completely blocked from inside and no water can exit the machine. Removing the plug immediately restores full drainage.

How do I manually drain standing water from my dishwasher before troubleshooting?

Use a large cup or ladle to scoop water out of the tub and into a bucket. Then place folded towels on the tub floor and press them flat to absorb the remaining shallow water before lifting them out. This gives you clear access to the filter, sump, and pump area for inspection without water spilling when you remove components. Always unplug the machine before reaching inside.

Also Read:

• Why Your Bosch Dishwasher Won’t Drain and Its Fix
• Why Your Dishwasher Runs But Leaves Dirty Dishes and Its Fix

Work From the Filter Out and the Fix Is Almost Always Right There

A dishwasher not draining completely has one of the most well-defined fix hierarchies of any appliance problem. Start with the filter every single time. Then move to the hose, the disposal connection, and the air gap before considering any mechanical component.

Those four free checks resolve the vast majority of dishwasher drainage complaints without a single tool or replacement part. For related reading and fixes, check out our dishwasher troubleshooting guide, where you get to learn about how you can troubleshoot various dishwasher problems.