How to Fix a Dishwasher That Isn't Draining
A dishwasher that leaves standing water in the bottom after a cycle is a common problem. In most cases, the fix is straightforward and doesn't require a technician. This guide walks through the most likely causes and how to address each one.
Safety First
Turn the dishwasher off and unplug it before inspecting. If your dishwasher is hardwired, switch it off at the circuit breaker. Clear any dishes and utensils from the machine before starting your inspection.
Step 1: Check and Clean the Filter
The most common cause of a dishwasher not draining is a clogged filter. The filter sits at the bottom of the dishwasher interior, usually under the lower spray arm. Twist and lift the filter assembly out and rinse it thoroughly under running water, using a soft brush to remove food particles and grease. Reinstall it correctly — a loose filter can also cause draining problems.
Step 2: Inspect the Drain Hose
The drain hose runs from the bottom of the dishwasher to the sink drain or garbage disposal. Check for kinks, bends or blockages along its length. If the hose connects to a garbage disposal unit, ensure the knockout plug has been removed (a common installation oversight that causes immediate draining failure). The drain hose should form a high loop under the sink to prevent back-siphoning from the drain into the dishwasher.
Step 3: Check the Air Gap or Drain Connection
If your dishwasher has an air gap fitting on the sink (a small cylindrical fitting near the tap), remove its cap and clean out any debris. Blockages here can prevent the dishwasher from draining. If there is no air gap, check that the drain hose is looped up high under the sink before connecting to the drain.
Step 4: Test the Drain Pump
If the filter and drain hose are clear, the drain pump may be blocked or faulty. Access the pump area at the bottom interior of the dishwasher (remove the lower spray arm and filter assembly). Check for glass fragments, bones or debris that may have bypassed the filter and lodged in the pump impeller. Remove any debris carefully. If the pump runs but doesn't drain (you can hear it humming), the pump may need replacement — a technician job.
Step 5: Run a Drain Cycle Test
After completing the above checks, run the dishwasher on a short cycle and observe whether it drains properly. If it still doesn't drain, check whether your sink drain itself is blocked — a blocked sink drain will prevent the dishwasher from draining into it.
When to Call a Technician
Call a technician when: the pump is audible but not draining; you find broken glass in the pump area; the control board may have failed; or you've completed all the above steps and the problem persists.
Need a New Dishwasher?
If your dishwasher is older and repairs are uneconomical, Oceania Appliances stocks dishwashers from Bosch, Miele, Fisher & Paykel, Electrolux, AEG, Samsung and more. Free delivery across Sydney. Visit 2/14 Centre Place, Wetherill Park (open 7 days, 10am–8pm), call or WhatsApp 0422 489 492, or email support@oceaniaappliances.com.au.