Right then. There’s nothing quite like the sinking feeling of opening your dishwasher after a cycle, expecting sparkling clean dishes, only to find them sitting in a pool of murky, leftover water. It’s a real pain, and a surprisingly common problem.
But before you throw your hands up and call a pricey tradie, no worries. Most of the time, a dishwasher that won’t drain is a problem you can sort out yourself with a bit of know-how and about half an hour. This is a common issue caused by a simple blockage.
This guide will walk you through the most likely culprits, from quick 1-minute checks to a more thorough inspection, so you can get your dishwasher back to doing the hard yakka for you.
Safety First, Mates! & What You’ll Need
Before you dive in, the most important step is to disconnect the power. Water and electricity are not mates.
- Turn it off: Unplug the dishwasher from the wall socket. If you can’t reach the plug, switch it off at your home’s main circuit breaker.
You’ll likely need a few things from around the house:
- Old towels or rags (it might get a bit messy)
- A cup or a small bucket to scoop out water
- A screwdriver (usually a Phillips head)
- Pliers
- An old toothbrush or a soft brush
- A torch (flashlight) to see into the dark corners
- Optional: A wire hanger or a small drain snake
The Quick Fixes (Before You Get Your Hands Dirty)
Let’s start with the easy stuff. Give these a go before you start taking things apart.
1. Run Your In-Sink-Erator (Garbage Disposal)
Your dishwasher’s drain hose usually connects to the sink’s plumbing, often via the garbage disposal unit. If the disposal is full of food scraps, it can block the dishwasher drain pipe, causing water to back up.
What to do: Turn on the cold tap and run your garbage disposal for about 30 seconds to clear any blockage. This simple action can sometimes be all it takes to solve the problem. Run a ‘Rinse’ cycle on your dishwasher to see if it now drains.
2. Check the Cycle & Run a “Drain” Cycle
Sometimes, a power flicker or accidentally opening the door mid-cycle can interrupt the process before it completes the final drain.
What to do: Close the dishwasher door securely and try selecting a “Rinse” or “Drain Only” cycle. Let it run completely. If it drains, you’re all sorted. If not, it’s time to move on to finding the physical blockage.
Finding and Cleaning the Clog (The Step-by-Step Guide)
If the quick fixes didn’t do the trick, there’s likely a physical clog somewhere in the system. Let’s get cracking.
Step 1: Get Rid of the Manky Standing Water
You can’t work on the drain if it’s underwater.
- Lay down your towels around the base of the dishwasher.
- Use a cup or small jug to scoop out as much of the standing water as you can.
- Use a sponge and more towels to mop up the remaining water at the bottom of the tub until it’s dry.
Step 2: Locate and Clean the Dishwasher Filter (The Usual Suspect)
This is the number one cause of a clogged dishwasher. The filter is designed to catch food debris, but over time it can get blocked up.
- Locate it: The filter assembly is almost always at the bottom of the dishwasher tub. Remove the bottom rack, and you’ll see it near the base of the main spray arm.
- Remove it: Most modern filters can be removed by twisting them counter-clockwise. Some may have a mesh screen and a cylindrical filter. Your owner’s manual will have a specific diagram if you’re not sure.
- Clean it: Take the filter pieces to the sink and rinse them under hot water. Use a soft brush or an old toothbrush to gently scrub away any caked-on gunk and food particles. Don’t use a wire brush or anything abrasive, as you could damage the fine mesh.
- Replace it: Once it’s sparkling clean, put the filter back in place and lock it securely. A loose filter can cause major damage.
Filter Types
While most modern dishwashers have a manual-clean filter like the one described, older models might have a hard food disposer (a self-cleaning system with a grinder). If you don’t see a removable filter basket, you likely have the self-cleaning type. If so, a blockage there is less common and the problem is likely further down the line.
Step 3: Inspect the Drain Hose for Kinks and Blockages
The drain hose is the ribbed plastic pipe that carries the wastewater from the dishwasher to your sink plumbing.
- Look for Kinks: Gently pull the dishwasher out from the counter a little. Check the entire length of the hose for any sharp bends or kinks that could be restricting water flow, much like a kinked garden hose. Straighten it out if you find any.
- Check for Clogs: If it’s not kinked, the clog might be inside. Place a bucket and some towels under the sink where the drain hose connects to the garbage disposal or sink pipe. Use pliers to loosen the clamp holding it in place, then disconnect the hose. Check both the hose opening and the connection point for blockages. You can try clearing a stubborn clog with a straightened wire coat hanger or a small drain snake.
Step 4: Clear the Sink’s Air Gap or Garbage Disposal Connection
If your sink has a small metal cylinder on top (usually next to the tap), that’s an air gap. It’s an anti-siphon device that can get clogged.
- Clean the Air Gap: Pull the metal cover off the air gap cylinder. Then, unscrew the plastic cap underneath. Clean out any debris you find inside with a brush.
- Check the Disposal Knockout Plug: If your garbage disposal is newly installed, the installer may have forgotten to remove the knockout plug where the dishwasher hose connects. If you disconnect the hose and see this plastic plug is still in place, carefully punch it out with a screwdriver and hammer, then retrieve the plastic piece from inside the disposal.
When to Call a Plumber or a Tradie
If you’ve tried all the steps above and your dishwasher still isn’t draining, the problem might be more serious. It’s time to call in a professional if:
- You suspect the drain pump is broken (you might hear a humming or clicking noise but no draining).
- The issue is with your home’s main plumbing lines, not the dishwasher itself.
- You’re simply not comfortable performing any of these steps. It’s always better to be safe than sorry.
Frequently Asked Questions (FAQ)
- Why is there standing water in the bottom of my dishwasher?
The most common reason is a clog somewhere in the drainage system. This is usually caused by food debris in the filter, but can also be due to a blocked drain hose or a full garbage disposal. - How do you force a dishwasher to drain?
You can’t “force” it in the traditional sense, but you can manually trigger a new drain cycle. The easiest way is to press “Cancel” and then select a “Rinse Only” or “Drain” cycle and press Start. This will activate the drain pump. If it doesn’t drain then, you have a physical blockage or a mechanical issue. - How often should I clean my dishwasher filter?
It’s a good habit to check it weekly for large particles and give it a thorough clean under the tap at least once a month to prevent build-up.