Dishwasher Not Draining? How to Fix Standing Water
Updated September 18, 2026
Can I do this myself?
DIY with precautions
Yes, the common fixes (filter, hose, air gap, sink drain) are safe DIY jobs once the dishwasher is switched off at the plug or circuit. Replacing the drain pump or working on wiring is best left to a technician.
A little moisture in the bottom of a dishwasher after a cycle is normal. A pool of dirty water covering the base is not. When a dishwasher won’t drain, the cause is usually a blockage somewhere along the path the water takes out: the filter in the tub, the drain pump, the drain hose, the air gap on the sink (if you have one) and finally the sink drain or garbage disposal it connects to.
Most of these can be checked in under an hour with a screwdriver, a towel and a bucket. The single most common cause is a clogged filter, which many people don’t realise needs cleaning at all. The second is a kinked or blocked drain hose, and on a newly installed dishwasher connected to a garbage disposal, the classic culprit is a knockout plug that was never removed.
Work through the checks in order, from the easiest to the most involved. Because you will be handling water close to electrical parts, switch the dishwasher off at its plug or circuit before you start.
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Signs of the problem
- Standing water in the bottom of the tub after a cycle finishes
- Dirty water or food particles left on the filter area
- The cycle stops or shows an error code related to draining
- A humming or buzzing sound during the drain part of the cycle, with no water leaving
- Water backs up into the kitchen sink or out of the air gap on the countertop
- A bad smell from the dishwasher
Common causes
Clogged filter
Most commonMost modern dishwashers have a removable filter under the lower spray arm that traps food. When it clogs with grease and debris, water can’t reach the drain pump. It should be cleaned regularly, often monthly with heavy use.
Kinked or blocked drain hose
Most commonThe corrugated drain hose behind or under the dishwasher can kink when the unit is pushed back, or clog with food and grease where it connects to the sink drain or disposal.
Knockout plug still in the disposal
SometimesNew garbage disposals have a plastic plug sealing the dishwasher inlet. If a dishwasher was connected to a new disposal without knocking it out, the dishwasher can never drain. This only applies to new installs.
Clogged sink drain, disposal or air gap
SometimesThe dishwasher drains into the sink plumbing. A slow kitchen sink, a full disposal or a blocked air gap (the small cap on the countertop beside the faucet in some homes) will stop it draining.
Failed drain pump or blocked impeller
Less commonBroken glass, fruit seeds or labels can jam the drain pump impeller. If the pump hums without moving water, or makes no sound at all during draining, it may be blocked or have failed.
Safety first: before you start
- Critical:Switch the dishwasher off, then unplug it or switch off its circuit at the breaker or fuse box before reaching into the tub or pulling the unit out.
- Critical:Let hot water and the heating element at the bottom of the tub cool before you reach in.
- Wear gloves when cleaning the filter and sump area. Broken glass is often the cause of a blockage.
- Lay towels on the floor and keep a bucket and shallow dish ready. Dishwasher water can spill over quickly when you open the filter or hose.
- If you also switch off power to the garbage disposal, do it at the plug or breaker before touching it.
Tools & materials
Tools
- Screwdriver set
- Plastic cup or small container (for bailing water)
- Bucket and old towels
- Soft brush (an old toothbrush works)
- Pliers
- Flashlight
Materials
- Rubber gloves
- Warm soapy water
- White vinegar or dishwasher cleaner (optional)
Step-by-step fix
- 1
Cancel the cycle and cut the power
If the dishwasher is mid-cycle, try a Cancel or Drain command first (often by holding Start or a specific button for a few seconds; check your manual). If it still won’t drain, switch it off and unplug it or turn off its circuit.
- 2
Remove standing water
Take out the lower rack. Scoop the water out with a cup into a bucket, then soak up the last of it with towels or a sponge. You need the sump area mostly dry to see what you are doing.
Warning: If the water is hot, wait for it to cool. The heating element sits in the base of many tubs and can stay hot for a while.
- 3
Clean the filter
Find the filter in the bottom of the tub, usually a cylinder under the lower spray arm that twists a quarter turn to unlock, with a flat mesh screen beneath it. Lift both out, rinse under a tap, and scrub with a soft brush and warm soapy water until the mesh is clear. Wipe out the sump opening and check for glass, seeds or labels.
Tip: If your dishwasher has no removable filter, it may have a self-cleaning grinder. In that case, check the hose and sink drain next.
- 4
Check the kitchen sink and disposal
Run water in the kitchen sink. If it drains slowly, the dishwasher can’t drain either, so clear the sink first. If you have a garbage disposal, run it for 20 to 30 seconds with cold water to empty the chamber, since the dishwasher hose connects into it.
- 5
Clear the air gap if you have one
An air gap is a small chrome or plastic cylinder on the countertop or sink next to the faucet. Pull or twist off the cover, unscrew the inner cap and clean out any debris with a small brush. If water was spilling from it during the cycle, a clog here or downstream is likely.
- 6
Inspect the drain hose
Under the sink, follow the dishwasher drain hose. It should rise in a high loop or go to the air gap before dropping to the drain. Straighten any kinks. With a bucket under it, loosen the clamp where it joins the disposal or drain, pull it off and check the end for a plug of food or grease. Blow through it or flush it with water to confirm it is clear, then refit and tighten the clamp.
Warning: Expect some dirty water to come out of the hose. Keep the bucket directly under the connection.
- 7
On new installs, remove the disposal knockout plug
If the dishwasher or disposal was just installed and has never drained, the knockout plug is the likely cause. Cut power to the disposal. Remove the dishwasher hose from the disposal inlet, place a flat screwdriver against the plastic plug inside the inlet and tap it with a hammer until it breaks free. Then retrieve the loose plug from inside the disposal chamber with tongs or pliers, never your hand.
Warning: The disposal must be unplugged or switched off at the breaker. Never reach into the chamber with your fingers.
- 8
Restore power and run a test
Refit the filter and rack, plug the dishwasher back in or restore the circuit, and run a short rinse or drain cycle. Listen for the pump running and watch whether water leaves the tub.
- 9
Recognise a pump problem
If the filter, hose, air gap and sink are all clear but the dishwasher still won’t drain, and you hear humming or nothing at all during draining, the drain pump or its impeller may be blocked or faulty. Some models let you remove a pump cover in the sump to check the impeller; follow your manual, or book an appliance technician.
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How to check it's fixed
- The tub is empty apart from a small amount of moisture after a full cycle
- No water backs up into the sink or out of the air gap during draining
- No leaks under the sink or from beneath the dishwasher
- No drain error codes on the display
When to stop and call a professional
- The drain pump hums or is silent and the filter, hose and sink are all clear
- You see water leaking from under the dishwasher onto the floor
- There is a burning smell, scorch marks or the breaker trips when the dishwasher runs
- The drain hose is split or needs replacing and you aren’t comfortable pulling the unit out
- The kitchen sink drain itself stays clogged after basic clearing
How to prevent it
- Clean the filter every few weeks, or monthly with light use.
- Scrape plates into the bin rather than relying on the dishwasher to handle large food scraps.
- Run the garbage disposal before starting the dishwasher.
- Make sure the drain hose keeps a high loop and isn’t crushed when the dishwasher is pushed back in.
- Run an empty hot cycle with dishwasher cleaner or vinegar occasionally to cut grease.
Frequently asked questions
Is it normal to have some water in the bottom of a dishwasher?
A small amount of water around the filter or sump is normal on many models, as it keeps seals moist. A pool covering the base of the tub, especially dirty water, means it isn’t draining properly.
Why won’t my new dishwasher drain?
If it is connected to a garbage disposal, the knockout plug in the disposal’s dishwasher inlet is the most likely cause. It must be knocked out with a screwdriver and hammer, and the loose plug removed from the disposal, with power off.
Can I use drain cleaner in my dishwasher?
No. Chemical drain cleaners can damage the pump, seals and hoses, and leave residue on dishes. Clear blockages by cleaning the filter, hose and sink drain instead.
Does baking soda and vinegar unclog a dishwasher?
It can help loosen light grease in the sump, but it won’t clear a solid blockage in the hose, a jammed pump or a knockout plug. Clean the filter by hand first and check the hose.
How do I know if my dishwasher drain pump is bad?
Signs include a humming sound with no water leaving, no sound at all during the drain phase, or a drain error code, all with the filter, hose and sink confirmed clear. A technician can test the pump and replace it if needed.
This guide is general information, not professional advice. Homes differ, so follow your product manuals and local codes. If anything looks different from what's described, or you feel unsure, stop and call a qualified professional. In an emergency, leave the area and call your local emergency number.
Related guides
Jammed garbage disposal
DIY with precautionsYes, most jams are a safe DIY fix if the disposal is unplugged or its circuit is switched off first and you never put your hand inside. The risks are serious hand injury and electric shock, both avoidable.
Slow-draining sink
Safe to DIYYes, clearing a slow sink drain is a safe DIY job with basic tools. Skip chemical drain cleaners, and call a plumber if several drains back up at once or dirty water comes up in other fixtures.
Leak under sink (P-trap)
Safe to DIYYes, a leaking P-trap is one of the easiest plumbing repairs. It is a low-pressure drain part, so there is no need to shut off the water, just stop using the sink. Call a pro if the leak comes from the wall pipe or the cabinet floor is rotting.
Washer not draining
DIY with precautionsUsually yes. Most drain problems are a clogged pump filter or a kinked hose, which you can fix yourself once the machine is unplugged. The real risks are water near electricity, hot water, and a flooded floor, so prepare before you open anything.