Dishwasher Not Draining? 7 Causes and How to Fix Them

Dishwasher Not Draining? 7 Causes and How to Fix Them

Opening your dishwasher to find standing water at the bottom is one of the most frustrating kitchen moments — dirty dishes, a foul smell, and no obvious explanation. When a dishwasher is not draining, the problem is almost always somewhere along the drainage pathway between the tub and the sink. The good news is that around 60% of the time, the cause is a blocked filter, which you can clear yourself in five minutes without tools. For the remaining cases, the issue is typically a clogged drain hose, a jammed drain pump, a stuck check valve, or a problem at the sink connection — all of which are DIY-repairable if you work through them methodically.

This guide covers all 7 causes of a dishwasher not draining, ordered from most to least common. It applies to Bosch, Fisher & Paykel, LG, Samsung, Electrolux, Westinghouse, Smeg, and other major brands available in Australia.

In This Guide

1. Before You Start
2. Quick Checks First
3. Cause 1 — Blocked Filter Basket
4. Cause 2 — Clogged or Kinked Drain Hose
5. Cause 3 — Faulty or Jammed Drain Pump
6. Cause 4 — Blocked Check Valve
7. Cause 5 — Problem at the Sink or Garbage Disposal Connection
8. Cause 6 — Blocked Air Gap
9. Cause 7 — Control Board or Door Latch Fault
10. When to Call a Technician
11. Parts You Might Need
12. Common Questions

Before You Start: Safety and Initial Checks

Before investigating why your dishwasher is not draining, turn it off at the wall and unplug it or switch it off at the circuit breaker. If there’s standing water in the tub, bail it out with a cup or bowl and mop up the excess with towels before you start inspecting components — working around water near electrical components is a safety hazard, and getting a clearer view of the filter and pump area makes the job much easier.

It’s also worth running a hard reset before you do anything else. Turn the dishwasher off at the circuit breaker for 5 minutes, then back on, and run a short drain cycle. Modern dishwashers sometimes get stuck mid-cycle due to a momentary power fluctuation or a control board glitch, and a reset clears it. If the dishwasher drains normally after a reset, you’re done. If it still won’t drain, proceed to the causes below.

Quick Checks That Rule Out the Simplest Causes

Before working through all seven causes in detail, check these three things first — they take under two minutes each and collectively resolve a significant number of dishwasher not draining calls.

First, check the sink. Run water into your kitchen sink and confirm it drains freely. If your sink is slow to drain or completely blocked, your dishwasher will share that blockage because its drain hose connects to the same drainage point. Fix the sink drain first. Second, check whether you’ve run a dishwasher cleaning product or the wrong detergent recently. Some household cleaners create excessive foam that can overwhelm the pump and prevent normal drainage. Add a cup of salt to the tub and run a short cycle — this breaks down foam rapidly. Third, check whether the dishwasher has an error code on its display. Note the code and look it up in your manual before continuing — many modern dishwashers have specific drain-circuit error codes (common ones include E4, F7, or DC) that point directly to the failed component.

Cause 1: A Blocked Filter Is Why Most Dishwashers Stop Draining

The filter basket at the base of the dishwasher tub is the first thing to check when your dishwasher is not draining, and it’s the cause in roughly 60% of cases. The filter’s job is to catch food particles, grease, and debris so they don’t reach the pump. When it isn’t cleaned regularly — and most households don’t clean it anywhere near often enough — it becomes so packed with accumulated waste that water can no longer pass through it into the pump intake. The result is standing water in the tub at the end of the cycle.

Finding and cleaning the filter takes five minutes and requires no tools. Look for a cylindrical plastic or stainless steel basket at the centre bottom of the tub, sometimes surrounded by a flat mesh filter plate. Twist it anti-clockwise or lift it straight out, depending on your model (your manual will confirm the exact mechanism). Hold the filter under warm running water and scrub it firmly with an old toothbrush or a soft-bristle brush, working the bristles through every section of the mesh. Rinse until water runs clear and there’s no visible grease or debris remaining. Check the filter seat in the tub — wipe it down with a damp cloth — and reinstall the filter, ensuring it clicks or locks into place properly. Run a short rinse cycle to confirm the dishwasher now drains normally.

Preventative cleaning: if your dishwasher runs daily, clean the filter once a week. For lighter use, fortnightly is sufficient. Scraping plates before loading significantly reduces how quickly the filter clogs.

Cause 2: A Clogged or Kinked Drain Hose Prevents the Dishwasher From Draining Fully

The drain hose connects the pump outlet to your sink drain or garbage disposal unit, running behind the dishwasher and through the cabinet space under the sink. If the hose kinks — particularly if the dishwasher was pushed back against the wall at an angle after a recent repair or cleaning — water can’t pass through it and the dishwasher won’t drain past the kink. A grease blockage inside the hose is a slower build-up problem: over months of use, particularly if the filter isn’t cleaned regularly, grease and food particles accumulate inside the hose and progressively reduce its flow capacity until drainage stops entirely.

Diagnosing the hose requires switching off the dishwasher and either pulling it out slightly or accessing the cabinet space under the sink. Trace the drain hose from the pump outlet to the sink connection and look for obvious kinks — these are usually immediately visible as a sharp bend in the corrugated plastic. If there’s no kink, disconnect the hose from the sink end (have a towel ready for the water), and pour warm water through it from a jug. If water flows freely, the hose is clear. If it barely trickles through, there’s a blockage — replace the hose rather than trying to clear it (a blocked drain hose that’s been accumulating grease for years rarely clears thoroughly). Drain hoses cost AUD $15 to $50 depending on your brand and the hose length. Replacement is a 15 to 20-minute job.

One important detail on installation: after the hose exits the cabinet under the sink, it should loop up as high as possible before descending to the drain connection — this high loop prevents water from the sink siphoning back into the dishwasher between cycles. If this loop is missing or has slipped down, it won’t directly prevent drainage, but it can cause back-contamination issues. Some Australian plumbing setups use an air gap fitting instead of a high loop — see Cause 6 if that applies to you.

Cause 3: A Faulty Drain Pump Is Stopping the Dishwasher From Draining

The drain pump is the motorised component at the base of the dishwasher that forces water through the drain hose under pressure at the end of each cycle. When the drain pump motor burns out or the impeller — the spinning blade inside the pump — gets jammed with broken glass, a fragment of bone, or a small piece of plastic, the pump can no longer move water. This produces a dishwasher that not only isn’t draining but typically makes distinctive sounds: a humming noise with no water movement usually means the impeller is jammed and the motor is running but can’t spin, while complete silence from the pump area during the drain sequence usually means the motor has burned out entirely.

To inspect the pump, switch the dishwasher off at the breaker, remove all the water from the tub, take out the filter and the spray arm assembly (usually one central bolt or a quarter-turn lock), and look down into the pump cavity at the centre bottom of the tub. With a torch, you should be able to see the impeller blades. Check for visible debris — glass fragments, plastic, bone shards, and pit-olive stones are the most common culprits. Remove any debris carefully with long-nose pliers or tweezers. Then try spinning the impeller gently with a finger or a wooden skewer — it should move freely with light resistance. If it won’t budge at all, the impeller is seized and the pump needs replacing. If it spins freely but the machine still won’t drain, the motor has failed and the pump needs replacing. Replacement drain pumps cost AUD $80 to $200 depending on your brand. It’s a moderately involved DIY repair — accessible from inside the tub on some models, requiring side-panel removal on others.

Cause 4: A Blocked Check Valve Is Stopping Water From Leaving the Dishwasher

The check valve — sometimes called the drain valve or non-return valve — is a one-way valve located at the pump outlet, just before the drain hose connection. Its job is to allow water to flow out during the drain cycle and then prevent already-drained water from being siphoned back into the tub. If grease or food debris gums up the valve and holds it in the closed position, the pump can run perfectly normally but water has nowhere to go. The symptom is often intermittent: the dishwasher drains sometimes but not reliably, or it drains partway then stops, or the pump sounds like it’s running but very little water actually moves.

Accessing the check valve requires the same disassembly as the pump inspection: tub emptied, filter removed, pump cover accessed. The check valve is typically a small plastic or rubber flapper or ball-type fitting directly at the pump outlet port. Inspect it for debris, grease buildup, or damage. Clean it thoroughly with a brush and warm water. If the valve is cracked, deformed, or won’t seat properly after cleaning, replace it. Check valves are inexpensive at AUD $20 to $60 and are often sold as part of a pump kit that includes the valve and associated seals. Replacing just the check valve rather than the entire pump is worth attempting if the pump impeller spins freely and the motor sounds healthy.

Cause 5: A Problem at the Sink or Garbage Disposal Connection Is Backing Up Into the Dishwasher

The dishwasher drain hose connects to either the sink drain tailpiece or a dedicated port on a garbage disposal unit under the sink. Two specific problems here can cause a dishwasher to stop draining — and both are easy to fix if you know to look for them.

The first is a blocked sink drain. If the sink drain has a partial blockage — which homeowners often don’t notice because water eventually drains through — the dishwasher’s drain pump may not be able to overcome the back-pressure. The fix is to clear the sink drain first, then retest the dishwasher. The second issue is specific to households where a new garbage disposal unit was recently installed. Garbage disposals have a knockout plug in the dishwasher inlet port that must be removed during installation. If the installer forgot to knock it out, the dishwasher drain hose is physically blocked from the moment it’s connected. This is the exact cause of a brand-new dishwasher that has never drained from day one. With the disposal switched off and unplugged, look inside the inlet port for the plastic knockout plug and remove it with a screwdriver. This is a single five-minute fix.

For a blocked sink drain that isn’t clearing with hot water, a plunger or a drain snake is the appropriate tool. If you have persistent grease blockages in an older kitchen, a plumber’s call-out is AUD $100 to $300 — worthwhile if the blockage is deep in the wall pipe.

Cause 6: A Blocked Air Gap Is Preventing Normal Dishwasher Drainage

Some Australian homes have an air gap fitting installed on the sink bench — a small chrome dome typically positioned just behind the kitchen tap. This fitting creates a physical air break in the drain line that prevents contaminated sink water from being siphoned back into the dishwasher. It’s a plumbing safety device required by some local council codes. When the air gap’s internal channels become blocked with mineral deposits or grease, the dishwasher can’t drain freely. The giveaway is water spurting or leaking from the chrome cap during the drain cycle — the pump is working, but the water has nowhere to go and pushes back out through the air gap.

Cleaning a blocked air gap takes five minutes. Unscrew the chrome cap anti-clockwise by hand (or with padded pliers if it’s tight), remove the inner plastic cap, and use a small brush or pipe cleaner to scrub the internal channels clear of deposits. Rinse thoroughly under running water until both chambers run clear. Screw the cap back on and run a test drain cycle. If the fitting is visibly cracked or damaged, replacement air gap fittings cost AUD $30 to $80 at plumbing supply stores.

Cause 7: A Control Board or Door Latch Fault Is Preventing the Drain Cycle From Completing

If you’ve worked through Causes 1 to 6 and the dishwasher is still not draining, the issue is likely in the electrical controls rather than the drainage hardware. The most common electrical causes are a faulty door latch that prevents the cycle from completing (the machine halts mid-cycle as a safety measure when it can’t confirm the door is properly closed) and a failing control board that stops the drain sequence from being triggered.

Check the door latch first: close the door firmly and listen for a solid click. If the latch is loose, broken, or worn, it may not register properly with the door switch. Inspect the latch assembly for cracked plastic tabs or a misaligned strike plate. A replacement door latch costs AUD $40 to $120 and takes around 30 minutes to replace on most models. If the door latches solidly but the drain cycle still won’t run, try a full hard reset (circuit breaker off for 5 minutes) and run a dedicated drain cycle. If an error code persists after the reset, the control board likely needs professional diagnosis. Control board replacement costs AUD $150 to $400 depending on the brand, and this is a job most homeowners hand to a technician.

When to Call a Technician About a Dishwasher Not Draining

Causes 1 through 6 are all practical DIY repairs. If you’ve cleaned the filter, flushed the hose, checked the sink connection, and inspected the check valve and air gap, and the dishwasher is still not draining, you’re most likely looking at either a failed drain pump or a control board fault — and this is where it’s worth weighing up the cost of a technician’s diagnosis against the age of the machine.

A technician call-out in Australia typically costs AUD $80 to $150 plus parts and labour. For a dishwasher under 5 years old, a drain pump replacement (AUD $80 to $200 for the part, AUD $80 to $150 for labour) is clearly worthwhile. For a machine over 10 years old with a control board fault, compare the total repair cost against the price of a replacement dishwasher — integrated dishwashers have come down significantly in price and a newer model may be more economical over a 5-year horizon. For Australian Consumer Rights guidance on faulty appliances, the ACCC’s repair, replace or refund guide explains your entitlements when an appliance fails within a reasonable period.

Parts You Might Need

All parts ship same-day from Sydney on orders received before the daily dispatch cutoff. $9.95 flat-rate shipping Australia-wide.

Drain Pump

AUD $80–$200 · Bosch, F&P, LG, Samsung, Electrolux, Smeg & moreFind your drain pump →

Check Valve

AUD $20–$60 · Non-return valve for pump outletFind your check valve →

Drain Hose

AUD $15–$50 · Universal and brand-matched optionsFind your drain hose →

Door Latch Assembly

AUD $40–$120 · Model-specificFind your door latch →

Filter Basket

AUD $20–$60 · Replacement filter assembliesFind your filter →

Find parts for your exact dishwasher model at OZ Appliance Spares — search by model number for confirmed compatibility, or get in touch and the team will identify the right part for you.

Common Questions

Why is my dishwasher not draining at the end of the cycle?

The most common reason a dishwasher is not draining at the end of the cycle is a blocked filter basket at the base of the tub. Food particles, grease, and debris accumulate in the filter and prevent water from flowing toward the pump. Start by removing and cleaning the filter — this fixes the problem around 60% of the time. If the filter is clean, the next most likely causes are a clogged drain hose, a jammed drain pump impeller, a stuck check valve, or a blocked connection at the sink drain. Work through each cause in the order listed in this guide.

Is it normal to have some water left in the bottom of my dishwasher?

A very small amount of water — a few millimetres at most — pooled directly below the filter basket is normal on most dishwasher models. This sits below the pump intake and doesn’t drain completely during normal cycles. However, if you can see a visible puddle covering the full floor of the tub, or if the water is dirty or has an odour, your dishwasher is not draining properly. A normal residual puddle is barely noticeable; a drainage problem leaves several centimetres of standing water clearly visible inside the tub.

How do I clean my dishwasher filter?

Open the dishwasher and locate the cylindrical filter basket at the centre bottom of the tub. Twist it anti-clockwise or lift it straight up — your manual confirms which. Hold it under warm running water and scrub it with a soft brush (an old toothbrush is ideal), working through all sections of the mesh until the water runs clear. Check for broken glass or sharp objects and remove them carefully with tweezers. Wipe the filter seat in the tub with a damp cloth to remove grease, then reinstall the filter and run a short test cycle. Clean the filter at least fortnightly if you run the dishwasher daily.

Can I replace a dishwasher drain pump myself?

Yes, if you’re comfortable working with basic electrical connections and following a model-specific guide. On most dishwashers, the pump is accessible from inside the tub after removing the filter, spray arm, and pump cover. You disconnect the pump’s electrical connector and hose connections, unbolt or unclip the pump housing, and install the new pump in reverse. It’s a moderately involved DIY task — typically 30 to 60 minutes — but achievable without specialist tools. If you’re uncertain about working around electrical connections, it’s safer to have a technician handle it. Replacement pumps cost AUD $80 to $200 depending on your brand.

My dishwasher stopped draining suddenly — could it be an error code?

Yes. Many modern dishwashers display a drain-related error code when the drainage circuit fails. Common codes include E4, F7, E24, or DC — though these vary by brand and model, so check your manual for the specific meaning on your machine. Before assuming the worst, try a hard reset: turn the dishwasher off at the circuit breaker for 5 minutes, then back on, and run a short cycle. If the code clears and the dishwasher drains, a momentary glitch caused the fault. If the code returns on the next cycle, the underlying cause needs to be diagnosed and repaired.

How do I know if my dishwasher drain pump has failed?

Two distinct symptoms point to drain pump failure. If you hear the pump running (a humming sound during the drain sequence) but water isn’t moving, the impeller is likely jammed with debris — glass, a small bone, a piece of plastic. If the pump is completely silent during the drain sequence when it should be running, the motor has likely burned out. You can also access the pump cavity through the base of the tub (with the filter removed) and try spinning the impeller gently — it should spin freely with slight resistance. If it won’t move at all, the pump is seized. If it spins freely but the machine still won’t drain, the motor has failed.

A dishwasher not draining is one of the easier appliance faults to resolve at home — particularly because the most common cause (a blocked filter) costs nothing to fix and takes five minutes. Work through the seven causes above in order, starting with the filter, and you’ll resolve the problem without a call-out fee in the majority of cases. If you do need a replacement part, OZ Appliance Spares stocks genuine and compatible drain pumps, check valves, drain hoses, and filter assemblies for all major brands, with same-day dispatch from Sydney and $9.95 flat-rate shipping Australia-wide.

Related guides: dishwasher spare parts guide

Frequently asked questions

Why is my dishwasher not draining at the end of the cycle?
Around 60% of the time it’s a blocked filter basket at the base of the tub — food, grease and debris packed so tight that water can’t reach the pump. Cleaning it takes five minutes and no tools. After that, check the drain hose, drain pump, check valve and sink connection in order.

Is some water in the bottom of a dishwasher normal?
A few millimetres pooled directly below the filter basket is normal on most models — it sits below the pump intake and never fully drains. A visible puddle covering the full floor of the tub, or water that’s dirty or smells, means the dishwasher isn’t draining properly and needs diagnosing.

How do I know if my dishwasher drain pump has failed?
Humming during the drain sequence with no water moving means the impeller is jammed with debris such as glass or bone; complete silence means the motor has burned out. With the filter out, spin the impeller gently — if it won’t budge, the pump is seized. Replacement pumps cost AUD $80-$200.

Why has my brand-new dishwasher never drained?
If a garbage disposal unit was recently installed, the installer may have forgotten to remove the knockout plug in its dishwasher inlet port — which physically blocks the drain hose from day one. With the disposal switched off and unplugged, remove the plastic plug with a screwdriver. It’s a five-minute fix.

How much does it cost to fix a dishwasher that won’t drain?
A technician call-out in Australia typically costs AUD $80-$150 plus parts and labour. In parts, a drain hose is AUD $15-$50, a check valve $20-$60, a drain pump $80-$200 and a control board $150-$400 — worth weighing against replacement on a machine over 10 years old.

Can I replace a dishwasher drain pump myself?
Yes, if you’re comfortable with basic electrical connections — it’s typically a 30-to-60-minute job with no specialist tools. On most dishwashers the pump is reached from inside the tub after removing the filter, spray arm and pump cover; disconnect the connector and hoses, unbolt, and fit the new pump in reverse.

Disclaimer: this article is general information only and is provided without warranty of any kind. Appliance designs vary between models and production runs — always follow the manufacturer’s instructions, switch off and unplug the appliance before starting any work, and confirm parts against the model number on your appliance’s model sticker. Any repair is undertaken at your own risk and Oz Appliance Spares accepts no liability for injury, loss or damage arising from work performed after reading this guide, to the maximum extent permitted by law. If in doubt, use a qualified technician.