The drain path runs filter, sump, pump, hose, disposal. Four of those five cost nothing to check, and one of them is why a brand new machine has never drained.
A dishwasher not draining leaves standing water in the sump because something on the path from filter to pump to hose to disposal is blocked. Four of those five checks are free, and the fifth, a drain pump, is the only one that costs real money.
Working them in order is the difference between a five-minute fix and a service call. A dishwasher not draining is one of the few appliance faults where the odds genuinely favour the free checks.
First, get the water out
Every guide starts here and none of them explain how, which matters because the sump holds more water than it looks like it does.
Cut power at the breaker, lay towels down before you begin, and scoop with a cup or a jug until you can finish with towels or a wet vacuum. Working in a dry tub makes everything after this straightforward.
The drain path, in order
Four checks before you call anyone
01
Cut power, then bail
Switch the circuit off at the breaker, lay towels down, and scoop the standing water out with a cup before finishing with towels or a wet vacuum.
02
Pull the filter and look underneath
Twist and lift the cylinder filter, wash it in warm water with a soft brush, then check the opening beneath it for glass, seeds and label paper.
03
Follow the drain hose
Look under the sink for kinks, and check the hose rises into a high loop before it drops. Without that loop, sink water siphons straight back into the machine.
04
Check the disposal connection
Run the disposal, then check the inlet nipple. On a new install, the knockout plug inside it is the single most common reason a dishwasher has never drained.
Dishwasher not draining? Start at the filter
Where does a dishwasher blockage usually sit?
In the filter assembly and the small opening beneath it. Grease binds food debris into a mat across the mesh, and hard fragments such as glass, olive stones and label paper lodge in the opening below where nobody looks.
Twist the cylinder filter counter-clockwise and lift it out. Wash it under warm running water with a soft brush until the mesh is genuinely clear rather than mostly clear.
Then look into the hole it came out of. That is the part almost every guide skips, and it is where the hard fragments end up.
New dishwasher? It is the knockout plug
This one fact resolves more brand new installations than everything else on this page combined.
Garbage disposals ship with the dishwasher inlet sealed by a moulded plug. The installer is supposed to knock it out before connecting the drain hose. When that step gets missed, the dishwasher is pumping against a solid wall and no amount of filter cleaning will change it.
A machine that has never drained once
If the dishwasher has worked correctly before, the knockout plug is not your problem. If it has never completed a cycle since installation and it drains into a disposal, check the plug before anything else. The symptom is a machine that sounds like it is draining and moves no water at all.
The drain hose and the high loop
The drain hose should rise to just under the countertop before dropping to the disposal or the standpipe.
That rise is the high loop, and it stops sink water siphoning back down into the machine. Installers skip it more often than they should, particularly in retrofits. While you are under there, check for kinks where the machine sits close to the wall and squeeze the hose along its length for soft spots.
High loop: hose secured up under the counter before it drops.
Kinks: commonly right behind the machine where it was pushed back into place.
Air gap: the small chrome cylinder on the sink, where local code requires one.
Sink drain: if the sink is slow, the blockage is plumbing rather than appliance.
Disposal, air gap and the sink side
Half the time a dishwasher is blamed for a plumbing problem it shares an outlet with.
Run the disposal for thirty seconds and then run the tap. A sink that drains slowly means the blockage is downstream of both appliances, and clearing it fixes the dishwasher as a side effect. An air gap fitted on the sink can also clog with debris and produce identical symptoms.
This is the last check rather than the first, because a blocked path makes a healthy pump sound exactly like a failing one.
Start a cycle and listen at the drain phase. A hum with no water movement suggests a jammed or failed pump. Total silence suggests the pump, its wiring or the control board. Either way, clear the filter and hose before spending anything, or you will replace a working part.
Can you force it to drain?
Is there a drain-only cycle?
On most machines yes. Holding the cancel button for a few seconds starts a cancel and drain routine that runs the pump and empties the tub. It clears the water so you can work, and it does not fix the underlying blockage.
Use it as a test as well as a convenience. A machine that empties fully on a forced drain and then fills up again during a normal cycle is telling you the pump works and something else is wrong.
Clear the filter basket and check the disposal knockout plug before calling anyone. Between them they account for most drainage complaints.
What this repair costs
Indicative US ranges. Always get a written quote.
Job
Typical range
Notes
Filter and sump clearing
no part cost
The most common cause by a distance
Knocking out the disposal plug
no part cost
New install that has never drained
Re-routing or replacing the drain hose
low-cost part
Kinks, pinholes and a missing high loop
Air gap cleaning
no part cost
Where local code requires one
Drain pump replacement
mid-cost repair plus diagnostic fee
Apply the 50 percent rule on an older machine
Source: Fixr 2026 appliance repair cost data, with part-level costs stated qualitatively where no published figure exists (retrieved August 2026). Figures vary by region, severity and after-hours timing.
Figures last checked
The top four rows cost nothing, which is unusual for an appliance fault and worth the twenty minutes before booking anyone.
Drawn from real public forum threads and reported prices, summarised and attributed as patterns.
These are not reviews of this site, and no names or ratings have been invented.
“What causes a dishwasher not to drain completely?”
SourceThread title from a community Q and A that ranks on this SERP. The recurring first answer is the filter and the sump, not the pump people fear.
“New dishwasher installed, will not drain, disposal is new too”
SourceA pattern repeated across appliance and plumbing forums. The consensus answer is the garbage disposal knockout plug, which ships sealed and has to be removed at install.
“Google AI Overview leads with removing standing water, cleaning the filter and checking the disposal inlet”
SourceThe live AI Overview for this query, citing Reddit, YouTube and manufacturer support. Useful confirmation that the free checks come first.
1 / 3
The knockout plug is the standout pattern in those discussions, because it is invisible from the machine and obvious once you know it exists.
How the matching works, and what we do not do
Emergency Services 24H is a referral service. We do not employ appliance technicians and we do not sell parts.
Your request routes by ZIP code to licensed, insured technicians covering your area, and they contact you directly. If the filter and the hose fix it, you owe us nothing and we would rather you tried them first.
Know the line
Safe to check yourself, or call a technician?
Safe to check yourself
Bailing the standing water with the circuit off
Removing and cleaning the filter assembly
Checking the drain hose for kinks and the high loop
Running the disposal and clearing the inlet
Cleaning an air gap on the sink
Call a pro now
Drain pump replacement
Any machine still under manufacturer warranty
Control board or wiring diagnosis
A leak that appears alongside the drainage fault
A drain problem shared with a slow or blocked sink line
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Get a licensed technician to diagnose it
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Straight answers
Frequently asked questions
The questions homeowners actually search for on this problem, answered in plain language.
Why is there standing water at the bottom of my dishwasher?
Because something on the drain path is blocked or has failed. In order of likelihood: the filter and the opening beneath it, a kinked or badly routed drain hose, a blocked garbage disposal connection, a clogged air gap, and finally the drain pump itself.
How do I force my dishwasher to drain?
Most machines have a cancel and drain function, usually triggered by holding the cancel button for a few seconds. It runs the drain pump and empties the tub, which is useful for clearing the water before you work on it. It does not fix whatever caused the blockage.
My new dishwasher has never drained. Why?
Almost certainly the garbage disposal knockout plug. Disposals ship with the dishwasher inlet sealed by a plug that the installer has to knock out. If it was missed, the dishwasher has nowhere to drain to, and no amount of filter cleaning will help.
How do I test a dishwasher drain pump?
Listen during the drain phase. A humming motor with no water movement suggests a jammed or failed pump. Complete silence suggests the pump, its wiring or the control board. Clear the filter and hose first, because a blocked path makes a healthy pump sound exactly like a dying one.
Is it the dishwasher or the sink?
Run the sink and the disposal first. If the sink drains slowly, the blockage is in the plumbing and the dishwasher is an innocent party sharing the same outlet. A sink that drains freely while the dishwasher holds water points back at the machine.
How much does it cost to fix a dishwasher that will not drain?
Nothing at all if it is the filter, the hose or the knockout plug, which covers most cases. A drain pump replacement is a mid-cost repair once labour and the diagnostic fee are included, which is the point at which the 50 percent rule is worth applying to an older machine.
The sump and filter basket
The drain hose high loop
A newly installed disposal with the knockout plug still in place is a classic cause, and it costs nothing to fix.
Tell us what has failed and where you are. We route your request to licensed, insured contractors covering your ZIP code, and they contact you directly.
Fire, a gas smell, or an injury? Leave the building and call 911 first, then your gas
utility or power company. Use this form once you are safe.
