Opening the dishwasher after a wash and finding dirty water in the bottom is frustrating, especially if you have no idea where to start.
When a dishwasher isn’t draining, the cause is often something fairly simple, such as a dirty filter or a kinked drain hose. Sometimes the problem sits farther along the kitchen waste pipe.
You can check many of these problems yourself without taking the whole appliance apart.
A dishwasher is usually easier to check than it looks because the first places to inspect are the filter and hose.
This guide shows you how to unclog a dishwasher that won’t drain, get rid of standing water and work out when it is time to call a professional.
Before you start, switch the dishwasher off at the wall and disconnect it from the electricity supply.
Why is there standing water at the bottom of my dishwasher?
A dishwasher with standing water has usually failed to empty at the end of the programme.
A small amount around the filter can be normal on some machines, but a pool across the bottom of the dishwasher is a different matter.
First, make sure the programme actually finished. If your machine has a cancel or reset setting, try resetting your dishwasher once.
Water left in the tub afterwards means there may be a blockage somewhere between the filter and the kitchen waste pipe.
Not sure how much water is normal for your dishwasher model? Consult your dishwasher manual before you start removing parts.
How do I know if my dishwasher is blocked?
The clearest sign is water not draining after a completed wash.
Listen while the dishwasher tries to empty. A humming sound with very little water moving often points you back towards the pump area.
Gurgling from the sink drain is different: that suggests the problem could be farther along the shared waste pipe.
You might also find old water around the filter or notice a stale smell when you open the door.
Those clues help you decide where to look first, but you will usually need to check the easy-to-reach parts before you know exactly what is wrong.
Is standing water always a problem?
Not always.
Standing water in a dishwasher is not always a fault because some machines retain a little water around the filter after a cycle.
What you do not want to see is standing water in your dishwasher spread across the base after the programme has finished.
If the dishwasher is blocked, that larger pool tends to stay put or come back after the next wash. At that point, move on to the filter and drain checks below.
What causes a blocked dishwasher? Get help with your drainage blockage
Most dishwasher blockages start in places you can inspect without special tools. To troubleshoot the problem, begin with the easiest checks.
A clogged dishwasher filter
The dishwasher filter catches food particles and other bits before they reach the pump. As grease and food build up on the mesh, they can keep water from draining freely.
A dirty filter often shows up as slower emptying before you ever get a completely full base. If the filter looks coated or packed with debris, clean it before you look anywhere else.
Filters do not all come out in the same way. Some twist and lift, others use a clip or locking piece.
One that refuses to move should not be forced, so check the instructions for your model if possible.
Food and debris causing a clog
Food particles are not the only things that cause a clog. Loose labels, pieces of packaging and tiny bits of broken crockery can end up inside of your dishwasher too.
Larger scraps are often caught in the filter. Finer material can slip past it and settle close to the drain pump, where even a small piece in the wrong place can block the flow.
It does not take much for a dishwasher to clog. The build-up can sit there for several washes before you notice anything is wrong.
A blocked or kinked drain hose
The drain hose is the flexible pipe that carries dirty water away from the machine. Look under the sink or behind the dishwasher and check that it has not been sharply bent or squashed.
This is especially worth doing if the dishwasher has recently been fitted or moved. A pinched dishwasher hose can stop the machine emptying even when the inside is clean.
The hose can clog internally as well, especially near the point where the drain hose connects to the kitchen waste pipe.
A blocked drain or pump fault
The drain pump pushes dirty water out of the dishwasher and into the hose. If a hard piece of debris reaches this area, it can jam the moving part inside the pump.
A faulty drain pump is a different problem. Clearing visible debris will not repair a failed motor or an electrical fault.
Some models let you reach the drain and pump area after the filter comes out. Only check the parts you can see and reach safely.
If that area is clear and the machine still will not empty, the pump itself becomes more likely.
A blocked sink waste or kitchen drain
The dishwasher may be fine and the blockage may be farther along the kitchen pipework.
In many UK homes, the hose connects the dishwasher to the waste pipe under the kitchen sink. A blockage there leaves water from your dishwasher with nowhere to go.
Check the sink too. If it is slow to empty or starts gurgling when the dishwasher drains, focus on the shared pipework instead of cleaning the same filter again.
What you need before you drain a dishwasher
As with other DIY unblocking jobs, like unblocking a toilet, it helps to have a few household items ready before you start.
Have a cup or small jug ready so you can scoop the water into a bucket. Keep a sponge nearby for what is left and put old towels around the dishwasher in case anything spills.
Gloves are worth wearing because bits of glass can be hard to see in cloudy water.
A soft brush or old toothbrush is useful when you clean your dishwasher filter.
With an integrated dishwasher, avoid pulling the machine out unless you know how it is fixed beneath the worktop. Most of the early checks can be done without moving it.
Safety checks before you drain your dishwasher
Disconnect the power before you reach into the base of the machine.
If you open a hose connection, expect some trapped water to come out. Put a container underneath first.
Do not remove covers that are not meant to come off during normal maintenance. The same goes for sealed electrical parts.
Avoid pouring ordinary drain cleaner into the dishwasher. Strong drain cleaner can damage seals or internal plastics.
Baking soda and vinegar is often suggested online, but soda and vinegar is not a universal fix for a blocked dishwasher either. For routine cleaning, use a dishwasher cleaner that is suitable for your machine.
How to unclog a clogged dishwasher in 5 steps
To unblock a dishwasher, start with the easy checks. A dirty filter takes minutes to deal with, so there is no reason to dismantle anything before you have ruled it out.
Step 1: drain the standing water
Start by removing the bottom rack. That gives you enough room to reach the base without leaning over the basket.
Use a cup or jug to drain the water into a bucket. Once the level is too low to scoop, soak up the remaining water with a sponge or towel.
As the bottom of your dishwasher comes into view, look out for food scraps or sharp fragments hidden under the water. This step does not clear the clog; it simply lets you see what you are dealing with.
Step 2: remove and clean the filter
Find the filter at the base of the machine. If your design lets you remove the dishwasher filter by hand, release it in the way shown in the manual and pull out the filter.
Rinse it under running water. Warm water usually loosens greasy residue, while a soft brush helps with anything stuck to the mesh.
Before you put the filter back, look at the opening underneath. Clear loose debris you can see, but do not push tools or your fingers into a hidden space.
Step 3: check the pump area
With the filter out, see whether your model lets you access the drain area. Some dishwashers have a small cover over the pump; on others, this part is closed off.
Look for obvious debris. A bit of glass or a hard food scrap in the wrong place is enough to cause trouble.
Some machines also let you check the small pump impeller. If yours does, make sure nothing is stopping it from turning. A dishwasher not draining properly after the accessible area has been cleared could have a pump fault.
Step 4: check the drain hose
Now move to the hose.
Start with the section under the sink or at the back of the machine. Straighten a visible kink and make sure stored items are not pressing against it.
Then look where the hose joins the kitchen waste pipe. Build-up at this connection can narrow the outlet and slow the flow.
Only remove the drain hose if the connection is easy to reach and you are ready for water to spill out. Put a bucket or shallow tray underneath before you loosen it.
Do not pull the whole machine from its fitted position just to reach a hidden connection unless you are comfortable doing so.
A clear hose alongside a slow-draining sink points farther into the kitchen pipework.
Step 5: put everything back and test
Refit the filter and any user-removable cover you took off. Make sure everything sits properly before you restore the power.
Run an empty dishwasher on a short programme or rinse cycle. When it reaches the drain stage, watch what happens.
If the water disappears normally, you have probably cleared the clog. If the dishwasher is still not draining, repeating the same checks is unlikely to help.
The fault could be in the pump, the drain valve or another internal part.
Step 5: put everything back and test
Refit the filter and any user-removable cover you took off. Make sure everything sits properly before you restore the power.
Run an empty dishwasher on a short programme or rinse cycle. When it reaches the drain stage, watch what happens.
If the water disappears normally, you have probably cleared the clog. To reduce the chance of it happening again, clean the filter regularly, scrape larger food scraps from plates and make sure the drain hose has not been kinked after the dishwasher is moved.
For more practical maintenance tips, read our guide on how to prevent dishwasher clogs.
When should you call Clark Drainage?
If your dishwasher problem is accompanied by a slow-draining sink, backing-up water or a blockage that keeps returning, the issue may be in the connected kitchen waste pipe or household drainage.
That is where Clark Drainage can help. Our experienced engineers can assess the drainage, locate the blockage and identify what is causing the problem before clearing the affected pipework.
Whether the blockage is close to the kitchen waste connection or farther along the drainage system, we have the equipment and experience to deal with problems that simple household checks cannot reach. You can find out more about our blocked drain services.
Call 0808 164 0776 for a free, no-obligation quote, or go to our contact page to arrange a visit from a local drainage engineer.
