What to Do If Your Dishwasher Is Not Draining

Woman unloading dishwasher in kitchen.
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Is your dishwasher not draining completely? Although your first thought might be that the dishwasher needs to be repaired or replaced, the problem could actually be with the plumbing and not the machine. If the water from the dishwasher encounters a blockage on its way to the drain pipe, it will have nowhere to go but back into the dishwasher. After you've checked the plumbing and ruled out a stoppage there, it's time to look at the machine itself.

Note: It's normal for some dishwashers to have a small amount of water at the bottom of the tub after a complete cycle. If you have just a little pool in your machine, check the owner's manual (or call the manufacturer) to see if this is by design. 

Check the Plumbing

Make sure the sink is draining. If your sink is not draining well the dishwasher will not drain, either.

Run the garbage disposal. In most cases, the dishwasher drain hose connects to the disposer. When there is food built up inside the disposer, or when the disposal is clogged, there is less space for the dishwasher water to go. Run the disposer thoroughly with plenty of water to clear it out.

Note: If you've just installed a new disposer, make sure the plug inside the nipple that accepts the dishwasher drain hose is knocked out. New disposers have a little plastic disc covering the drain opening. The disc must be punched out with a hammer and screwdriver. The disc just falls into the disposer's grinding chamber, and you have to fish it out. 

Clean the air gap. This is the small (usually chrome) cylinder on the back edge of the kitchen sink. If water comes out of the air gap (and sometimes all over the counter) when you run the dishwasher, the blockage is between the air gap and the garbage disposer. To clear it, remove the air gap cap and clean inside the air gap. Next, disconnect the hose between the bottom of 

Check the dishwasher drain hose. This is usually a corrugated plastic tube and is connected to the bottom of the dishwasher (behind the toe-kick panel under the dishwasher door) and to the air gap, disposer or sink drain, depending on your setup. 

Check the Dishwasher

Make sure there is nothing clogging the drain screen at the bottom of the dishwasher tub. Clear plastic lids, glass, labels, and bits of plastic can cover the drain and might be hard to see unless you look closely.

Clean the filter. Dishwashers can have a variety of filter designs. Some have a simple screen, some have removable filters below the screen, and some require removing the bottom spray arm for a thorough cleaning. 

Check the dishwasher drain hose. This is usually a corrugated plastic tube and is connected to the bottom of the dishwasher (behind the toe-kick panel under the dishwasher door) and to the air gap, disposer or sink drain, depending on your setup. ​

Turn off the power to the dishwasher by pulling out its plug or switching off the breaker to the dishwasher circuit. Remove the toe-kick panel, then loosen the hose clamp securing the drain hose to the dishwasher pump; have a rag handy for any water that spills out. Clean the end of the hose, then blow into it like you're Miles Davis. If the hose is plugged and you can't blow through it, remove the clamp on the other end and clean or replace the hose. 

Other Things to Check

If you've tried all of the above fixes and the dishwasher is still not draining, there are several dishwasher parts that could be at fault. Depending on your dishwasher model, these may include:

  • Check valve
  • Piston and nut assembly (on drain sump)
  • Drain pump and drain motor
  • Pump solenoid
  • Belt (on belt-driven pumps)
  • Timer
  • Door switch
  • Electronic control

Checking many of these parts requires a multimeter and some knowledge of electrical circuitry. It's best to leave this to a pro unless you have the expertise with this kind of diagnosis. Most dishwasher replacement parts are widely available online, using the machine's model number to find the right parts.