How to Fix a Dishwasher Not Draining: Step-by-Step Guide

A dishwasher that won't drain is a frustrating problem — but it's also one of the most common dishwasher issues and often something you can fix yourself. Here's a systematic guide to diagnosing and fixing a dishwasher that isn't draining properly.

Safety First

Before inspecting or working on your dishwasher, switch it off at the power point and unplug it. Use towels or a shallow tray to catch any water.

Step 1: Check the Filter

The most common cause of a dishwasher not draining is a blocked filter. The filter sits at the bottom of the dishwasher tub and catches food particles. If it's clogged, water can't drain.

How to clean the filter: Remove the bottom rack. Find the filter assembly at the bottom of the tub (it usually twists off). Rinse it under running water and use a soft brush to remove any debris. Reinstall it and run a short cycle to test.

Step 2: Inspect the Drain Hose

The drain hose runs from the dishwasher to your under-sink plumbing. It can become kinked, clogged, or disconnected. Check that the hose is not kinked or pinched — especially if the dishwasher was recently moved. Check the connection where the hose meets the sink drain or garbage disposal.

Step 3: Check the Garbage Disposal (If Applicable)

If your dishwasher drains into a garbage disposal, make sure the disposal isn't clogged and that the knockout plug was removed when the disposal was installed. Run the disposal to clear any blockage, then test the dishwasher.

Step 4: Check the Air Gap (If Applicable)

Some installations use an air gap — a small fitting on top of the sink. If the air gap is clogged, the dishwasher won't drain. Remove the cap and clean out any debris.

Step 5: Check the Drain Pump

If the filter, hose, and garbage disposal are all clear, the problem may be the drain pump. The pump can be blocked by small items (glass shards, bones, coins) that got past the filter. Access the pump area at the bottom of the tub (refer to your model's manual) and check for obstructions.

Step 6: Check the Door Latch and Float Switch

Some dishwashers won't start the drain cycle if the door latch or float switch isn't functioning correctly. The float switch (a small plastic dome in the base of the tub) prevents overfilling. If it's stuck in the up position, the dishwasher thinks it's full and may not drain. Gently lift and release the float to check it moves freely.

When to Call a Technician

If you've completed all the steps above and the dishwasher still won't drain, the drain pump motor may have failed and needs to be replaced. This is a job for a technician or appliance repairer.

Need a New Dishwasher in Sydney?

If your dishwasher is beyond repair, Oceania Appliances has a great range of certified refurbished dishwashers with 3-month warranty and free delivery across Sydney.