Dishwasher Not Draining? 12 Causes and Easy Fixes

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July 27, 2026
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Opening your dishwasher after a wash programme only to find standing water at the bottom is frustrating. Whether your dishwasher is not draining completely, leaves dirty water after every cycle, or simply won’t drain at all, the problem can quickly turn a convenient appliance into a major inconvenience.

The good news is that a dishwasher not draining doesn’t always mean an expensive repair or a replacement appliance. Often the source of the problem is food debris, a clogged drain line, a blocked dishwasher filter, or another issue you may recognise yourself.

In this article, we’ll go over the most common reasons your dishwasher won’t drain, how the dishwasher draining mechanism works, and practical repairs that can help restore your dishwasher to working order. We’ll also look at when it’s okay to make your own checks and when you need to call in a certified dishwasher repair engineer.

If you need expert help anywhere in Westminster or the surrounding areas of London, Westminster Appliances provides reliable domestic appliance repair services for most major brands.

Go to Westminster Appliances to find out more or arrange a repair.

Table of Contents

1. Clogged Dishwasher Filter

This is the first line of defense against food debris entering the drain pump.

Over time it can become clogged with:

Rice
Pasta
Eggshell
Coffee grounds
Grease
Glass fragments
Fruit seeds

How to Fix It

Turn off the power.
Remove the lower rack.
Twist out the filter.
Wash it under warm running water.
Reinstall securely.

Cleaning the filter monthly helps to reduce drainage problems greatly.

2. Blocked drain hose

A blocked drain pipe is another very common reason why a dishwasher will not empty.

Grease and bits of food build up slowly inside the hose, cutting down the flow of water.

Look for:

Twists
Kinks
Grease build-up
Loose connections.

Any visible damage Disconnect hose and flush well, if necessary.

3. Food particles blocking sump

Even if your filter is clean, dirt can still get into the sump.

Technicians often find :

Shards of broken glass
Lemon seeds Bones
Plastic Labels
Toothpicks
Small wrapping pieces

These objects can restrict water flow or cause the pump impeller jam problem. Remove these by properly cleaning the sump.

4. Jammed drain pump impeller

The impeller is a small rotating blade inside the drain pump. If it becomes blocked, the motor may still hum while little or no water leaves the appliance.

This is one reason why homeowners often report:

“My dishwasher is not draining but the pump works.”

Remove any visible obstruction carefully.

Never force the impeller.

5. Faulty Drain Pump

If the drain pump has failed electrically, the dishwasher cannot remove wastewater.

Symptoms include:

No drain noise
Standing water
Dishwasher won’t complete the cycle
Pump silent during drain programme

Drain pumps usually require professional replacement.

6. Blocked Household Waste Pipe

Sometimes the dishwasher isn’t actually the problem.A blocked kitchen waste pipe prevents wastewater leaving the appliance.

Simple test

Run your kitchen tap.If the sink drains slowly, the plumbing may need attention before investigating the dishwasher further.

Expert Tip

Regularly cleaning your dishwasher filter and checking for food debris can help prevent many common drainage issues.

You can also connect Westminster appliances if you find any issues in your dishwasher.

Quick Troubleshooting Checklist

Before calling an engineer, check the following:

✔ Clean the dishwasher filter

✔ Remove standing water

✔ Inspect the sump

✔ Check the drain hose

✔ Run a drain programme

✔ Listen for the drain pump

✔ Check whether the sink drains normally

Many drainage problems are solved within 15–30 minutes.

Dishwasher Not Draining But Filter Is Clean

A clean filter doesn’t necessarily mean the drainage system is clear.If your dishwasher not draining but filter is clean, the problem may involve:

Drain hose blockage
Pump impeller
Drain pump
Float switch
Water level sensor
Check valve
Control board

This is why a systematic diagnosis is important.

Dishwasher Not Draining But Pump Works

If you hear the pump running but water remains inside, consider some of these possibilities.

Possible Cause Likelihood
Partial drain hose blockage = High
Pump impeller jam = High
Blocked waste pipe = Medium
Check valve fault = Medium
Water level sensor issue = Medium

This situation often confuses homeowners because the pump appears to function normally.However, a blockage further along the drainage system can produce exactly the same symptom.

When Should You Stop DIY Repairs?

Some maintenance tasks are perfectly safe. These include:

Cleaning the filter
Removing debris
Checking the drain hose
Cleaning around the sump
However, stop immediately if you suspect:
Electrical faults
Burnt wiring
Control board failure
Water leaking near electrical components
Damaged pump motor
In these situations, professional diagnosis is the safest option.

7. Defective Float Switch or Water Level Sensor

Your float switch (or water level sensor) indicates how much water is in your dishwasher’s tub. It then informs the appliance when it is time to start the drain cycle after the wash programme has finished.

If the float gets stuck or the sensor does not work, your dishwasher might not drain properly, even if the pump and other parts are working.

Common Symptoms

The dishwasher fills but won’t drain.
Water remains after every cycle.
The drain programme doesn’t start.
The appliance stops unexpectedly.
The water level appears unusually high.

What You Can Check

Disconnect the dishwasher from the mains.
Locate the float (refer to your user manual).
Make sure it moves freely.
Remove any food debris or limescale around it.
If the sensor is faulty, it will usually need replacing by a qualified engineer.

8.Faulty Control Board

The control board is the “brain” of your dishwasher. It controls all the stages of the wash cycle including when the drain pump should engage.A malfunctioning control board can cause a variety of drainage issues.

Symptoms

The dishwasher washes normally but won’t drain.
Random programme stops.
Multiple error codes.
The drain pump works during testing but not during a normal cycle.
Lights flashing unexpectedly.

Electronic faults are difficult to diagnose without specialist equipment, so this repair is generally best left to an experienced appliance engineer.

9. Incorrect Drain Hose Installation

If you’ve recently installed a new dishwasher or had plumbing work carried out, the issue may not be inside the appliance at all.

An incorrectly installed drain hose can allow dirty water to flow back into the dishwasher after it has drained.

Common Installation Mistakes

No high loop in the hose.
The hose connected too low.
Loose hose connections.
Drain hose kinked behind the appliance.

These issues are particularly common after DIY installations.

10. Faulty Check Valve

The check valve keeps wastewater from coming back into the dishwasher after it has been pumped out. If this valve becomes stuck open or clogged, dirty water may flow back into the bottom of the appliance.

Signs of a Faulty Check Valve

Water reappears after draining.
Dirty water sits in the bottom overnight.
Persistent unpleasant smells.Intermittent drainage problems.

Although it’s not one of the most common faults, it’s frequently overlooked.

11. Broken or Collapsed Drain Hose

Drain hoses can wear out after a period of time. Even if the outside looks ok, the lining inside can collapse, restricting water flow.

Replace if you see:

Visible cracks.
Water leaks.
Persistent blockages.
Slow draining despite cleaning.

12. Air Gap or Waste Pipe Restriction (Where Applicable)

Some dishwashers use an air gap to prevent wastewater flowing backwards. If it becomes clogged with grease or food debris, water cannot drain properly.

Likewise, a blocked household waste pipe can prevent the dishwasher from emptying correctly.

If your kitchen sink is also draining slowly, the plumbing system may be responsible rather than the dishwasher itself.

Step-by-Step Dishwasher Troubleshooting Guide

Work through these checks before replacing expensive parts.

Step 1 – Switch Off the Power

Always disconnect the appliance from the mains before carrying out any maintenance. Safety should always come first.

Step 2 – Remove Standing Water

Use:

A jug
Towels
A sponge
A wet and dry vacuum

Removing the water makes the rest of the inspection much easier.

Step 3 – Clean the Filter

Even if it looks clean, remove it completely and rinse away grease and hidden debris.

Step 4 – Inspect the Sump

Look for:

Glass fragments
Food particles
Plastic labels
Fruit stones
Bones
Coffee grounds

Small objects often jam the pump impeller.

Step 5 – Check the Drain Hose

Inspect the entire hose for:

Kinks
Twists
Grease build-up
Blockages
Damage

Step 6 – Listen to the Pump

A healthy pump produces a smooth humming sound while moving water.

If you hear:

Grinding
Buzzing
Clicking
Complete silence

It means the drain pump may require professional attention.

Step 7 – Test the Kitchen Sink

Run the kitchen tap.If the sink drains slowly, the blockage may be within your household plumbing rather than the dishwasher.

Dishwasher Not Draining After Cleaning the Filter

Many homeowners assume cleaning the filter should immediately solve the problem.

Unfortunately, that’s not always the case.If your dishwasher not draining after cleaning the filter, investigate:

Pump impeller
Drain pump
Drain hose
Waste pipe
Float switch
Check valve
Control board

A clean filter only rules out one possible cause.

Dishwasher Not Draining After Every Cycle

If water remains after every wash programme, the issue is usually more than a temporary blockage.Possible causes include:

Possible Cause = Likelihood
Faulty drain pump = High
Blocked drain hose = High
Float switch failure = Medium
Control board fault = Medium
Check valve issue = Low

Brand-Specific Dishwasher Troubleshooting

Although the symptoms are similar, each manufacturer has its own common drainage issues.

Bosch Dishwasher Not Draining

Bosch models commonly experience:

E24 error
E25 error
Blocked filters
Pump impeller obstructions

Samsung Dishwasher Not Draining

Samsung dishwashers often display:

5C error
OC error
Drain pump issues
Water level sensor faults

Hotpoint Dishwasher Not Draining

Typical problems include:

Drain pump wear
Filter blockages
Control module faults

Beko Dishwasher Not Draining

Common causes include:

Pump failure
Drain hose restrictions
Float switch problems

Neff, Siemens, AEG, LG, Whirlpool, Indesit and Miele

These brands generally suffer from the same common drainage faults:

Blocked filters
Pump failures
Clogged drain hoses
Electronic faults
Water sensor issues

Always consult your appliance manual before dismantling any components.

Common Dishwasher Error Codes

Modern dishwashers often display an error code when drainage problems occur.

Brand	Common Drain Error Code(s)
Bosch	E24, E25
Samsung	5C, OC
Beko	H5 (model dependent)
Hotpoint	F11 (model dependent)

Always check your specific model’s manual, as error codes can vary.

DIY Repair vs Professional Repair

Problem	DIY	Professional
Clean dishwasher filter	✅
Remove food debris from sump/filter	✅
Inspect drain hose for kinks or blockages	✅
Remove standing water	✅
Replace drain pump		✅
Replace control board		✅
Electrical diagnosis		✅
Replace water level sensor (float switch)		✅

If you’re ever unsure, it’s always safer to seek professional assistance.

Dishwasher Repair Costs in the UK

Repair costs vary depending on the appliance brand and the fault.

Repair	Typical Cost (UK)
Diagnostic visit	£60–£120
Drain pump replacement	£120–£220
Drain hose replacement	£80–£150
Float switch replacement	£90–£180
Control board replacement	£180–£350

In many cases, repairing a modern dishwasher is considerably more cost-effective than replacing it.

How to Prevent Dishwasher Drainage Problems

Regular maintenance can prevent many common issues.

Weekly

Scrape large food scraps from dishes.
Check the filter for debris.

Monthly

Remove and clean the filter.
Wipe the sump area.
Clean the spray arms.

Every Six Months

Inspect the drain hose.
Check for leaks.
Clean the door seals.

Yearly

Once a Year Arrange a professional service if your dishwasher is heavily used. Preventative maintenance can prolong its lifespan and reduce the likelihood of unexpected breakdowns.

Why Choose Westminster Appliances?

Westminster Appliances has helped customers in Westminster and London with a range of dishwasher drainage issues, from simple blocked filters to more complicated drain pump and control board problems.

Bosch, Samsung, Beko, Hotpoint, Neff, Siemens, AEG, LG, Whirlpool, Indesit, and Miele are just a few of the top domestic appliance manufacturers that our engineers work with.

If you’ve followed the troubleshooting procedures in this tutorial and your dishwasher is still not emptying, we’re here to assist.

Commonly Asked Questions

Why is my dishwasher not draining but still running?

This usually indicates a blocked drain hose, a jammed pump impeller, or a faulty drain pump.In some cases, the control board may not be completing the drain cycle correctly.

Why is there standing water in the bottom of my dishwasher?

Standing water is commonly caused by a blocked filter, clogged drain hose, faulty pump, or restricted household waste pipe.

Can I manually drain my dishwasher?

Yes.Switch off the power first, then remove the water using a jug, sponge, or wet and dry vacuum before investigating the cause.

Can a blocked sink stop a dishwasher from draining?

Yes.If your kitchen sink or waste pipe is blocked, wastewater may not be able to leave the dishwasher efficiently.

Should I use chemical drain cleaners?

No.Chemical drain cleaners can damage seals, hoses, and internal components.They can also create safety hazards during repairs.

Is it worth repairing a dishwasher that won’t drain?

In many cases, yes.

Problems such as blocked filters, drain hoses, or even drain pumps are usually much cheaper to repair than replacing the entire appliance.

Final Thoughts

A dishwasher not draining is one of the most common appliance problems, but it’s rarely a reason to replace your dishwasher straight away.

By checking the filter, drain hose, pump impeller, and waste pipe first, you can often identify the cause and restore normal operation without unnecessary expense.

If the problem persists or involves electrical components such as the control board, float switch, or drain pump, it’s best to contact a qualified repair engineer.

At Westminster Appliances, we specialise in repairing domestic dishwashers throughout Westminster and across London.Whether you have an integrated dishwasher, built-in dishwasher, or freestanding model, our experienced engineers can quickly diagnose the issue and recommend the most cost-effective solution.

Need help with a dishwasher that won’t drain? Visit

https://www.westminsterappliances.co.uk/ to book a trusted local repair today.

Dishwasher Not Draining? 12 Causes and Easy Fixes