Quick Fix: Most dishwasher drainage issues are caused by a clogged filter or a blocked garbage disposal. Clear the filter at the bottom of the tub and run your disposal to ensure the path is clear. If that doesn't work, check the air gap or drain hose for kinks.
Diagnose the Problem
A dishwasher that won’t drain is one of those “emergencies” that usually takes more time to mop up than it does to fix. Before you call a plumber, you need to figure out where the water is getting stuck.
| Symptom | Likely Cause |
|---|---|
| Standing water with food debris | Clogged filter or sump |
| Water backing up into the sink | Blocked disposal or air gap |
| Humming noise but no drainage | Defective drain pump |
| Water drains slowly or smells | Partially blocked hose |
What You’ll Need
Also helpful:
- Dishwasher Air Gap Installation Kit, Everything needed to replace a clogged air gap system.
- Shop towels (you’re going to get wet)
- A small bucket or shallow pan
Fix 1: Clean the Filter and Sump
Modern dishwashers have a filter system designed to catch food particles. If you haven’t cleaned yours in a few months, it’s likely choked with grease and debris, preventing water from reaching the drain pump.
Steps:
- Remove the bottom rack, Pull it all the way out of the dishwasher.
- Twist and lift the filter, Most filters unlock with a quarter-turn. Lift the cylindrical filter and the mesh screen.
- Scrub and rinse, Use a soft brush and hot soapy water to clear the mesh.
- Check the sump, Feel inside the hole where the filter sits. If you find glass shards or pits, remove them carefully.
Time: 10 minutes
Fix 2: Clear the Disposal and Air Gap
The dishwasher drains through your kitchen sink plumbing. If the sink is clogged, the dishwasher can’t empty.
Steps:
- Run the garbage disposal, A disposal full of food will block the dishwasher’s drain line. Run it with plenty of water.
- Clean the air gap, If you have a small chrome cylinder on your sink, pull the cap off. Remove the plastic cover and check for blockages inside the tubes.
- Check the “knockout” plug, If you just installed a new disposal and the dishwasher won’t drain at all, you likely forgot to remove the plastic plug where the dishwasher hose connects.
Time: 15 minutes
Fix 3: Inspect the Drain Hose
The drain hose is a long, corrugated tube that runs from the dishwasher to the sink. If it’s kinked or sagged, water will stay in the tub.
Steps:
- Check for kinks, Look under the sink. If the hose is pinched by a bottle of detergent or a heavy pot, straighten it out.
- Verify the “High Loop”, The hose should be fastened high up against the underside of the counter before it drops down to the disposal. This prevents sink water from flowing back into the dishwasher.
- Disconnect and flush, Place a bucket under the connection, remove the hose, and blow through it. If it’s blocked, you may need a replacement hose.
Time: 20 minutes
Fix 4: Replace the Drain Pump
If the path is clear but the water won’t move, the motor that drives the water out (the drain pump) has likely failed. You’ll often hear a faint humming or clicking noise when it tries to start.
Steps:
- Turn off power, Unplug the dishwasher or flip the circuit breaker.
- Access the pump, Most modern units allow access by removing the bottom front panel (the kickplate).
- Swap the pump, Disconnect the wire harness, twist the old pump out, and click the new one into place.
Time: 45 minutes
When to Call a Pro
Most drainage issues are simple blockages you can clear yourself. However, call a professional if:
- You see signs of an electrical short or scorched wires.
- Water is leaking from the bottom of the machine onto the floor.
- You’ve replaced the pump and cleared the lines, but the control board isn’t sending a signal to drain.
FAQ
Why is there still a little water in the bottom? A small amount of clean water (about a cup) in the sump area is normal. It keeps the seals from drying out. You only have a problem if the water covers the filter or the floor of the tub.
Can I use Drano in my dishwasher? Absolutely not. Liquid drain cleaners are caustic and can damage the plastic parts and rubber seals inside your dishwasher.
How often should I clean the filter? If you don’t pre-rinse your dishes, clean it once a month. If you’re a “rinse before you wash” person, once every three months is usually enough.