How to Fix a Dishwasher That Won't Drain — Troubleshooting Guide

Standing water at the bottom of your dishwasher is one of the most common appliance problems. In most cases, it's a quick fix you can do yourself without calling a technician. Here's how to diagnose and resolve a dishwasher drainage problem.

Common Causes of Dishwasher Drainage Problems

• Blocked or dirty filter
• Kinked or clogged drain hose
• Blocked sink drain or garbage disposal
• Faulty drain pump
• Incorrect detergent causing excessive foam

Step 1: Check and Clean the Filter

The filter is the most common culprit. It sits at the bottom of the dishwasher and can get clogged with food scraps, grease and debris.

1. Remove the bottom rack
2. Twist and lift out the filter assembly (most models twist counter-clockwise)
3. Rinse under warm water, scrubbing gently with an old toothbrush
4. Reinstall the filter and run a short cycle to test

Step 2: Check the Drain Hose

The drain hose connects your dishwasher to the sink drain or garbage disposal. It can become kinked if the dishwasher was recently moved, or blocked with debris.

• Pull the dishwasher out slightly and inspect the hose at the back
• Ensure there are no kinks or sharp bends
• Disconnect the hose from the sink end and check for blockages

Step 3: Check the Sink Drain

If your sink drains slowly, that can back up into the dishwasher. Run hot water down the sink and check if it drains freely. Clear any blockage in the sink before testing the dishwasher again.

Step 4: Check the Garbage Disposal (if applicable)

If you have a garbage disposal unit connected to your dishwasher drain, run it for 30 seconds to clear any blockage. Also check the knockout plug — on new disposals, it needs to be removed when connecting a dishwasher.

Step 5: Check for Excessive Foam

Using regular dish soap instead of dishwasher detergent creates excessive suds that can prevent draining. If the drum is full of foam:

• Scoop out as much water/foam as possible
• Pour a cup of white vinegar into the bottom
• Run a short rinse cycle

When Is It the Drain Pump?

If none of the above fixes work, the drain pump may have failed. You'll often hear a humming sound but no water movement. This repair requires a technician or a replacement dishwasher.

Need a New Dishwasher?

If your dishwasher is old and repairs aren't worth it, Oceania Appliances stocks Bosch, Samsung, Fisher & Paykel and more. Free delivery across Sydney, 3–6 month warranty guaranteed.

Call: 0450 220 436 | Shop: oceaniaappliances.com.au