XT Appliances · Warren

Dishwasher won't drain

Often the water's way out is blocked at the filter or under the sink, and otherwise the drain pump has jammed or failed.

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At the end of each wash and rinse, the drain pump pushes the dirty water out of the sump (the basin at the bottom of the tub), through the drain hose and into your garbage disposal or the sink drain. A small one-way flapper in that path keeps the water from running back in. Standing water after a full cycle means something along that route has stopped it, and the simple causes sit at the two ends.

Start at the ends

Inside the tub, the filter under the bottom rack catches food before it reaches the pump. Packed full, it lets water through slowly or not at all, and you can usually see scraps and grit sitting on it. Rinse it and run a short cycle before you suspect anything else.

Under the sink is the other end. If the trouble started right after a new garbage disposal went in, the knockout plug in the disposal's dishwasher inlet was probably never removed, and the water has nowhere to go. If your sink has an air gap (the small cap beside the faucet), water spitting out of it or backing up into the sink when the dishwasher drains means the air gap or the hose past it is clogged. In both cases the pump itself is fine.

When it's the pump or the flapper

Listen near the end of the cycle. A drain pump that hums but moves no water is usually jammed, often on broken glass or a fruit pit, and not burned out. A pump that stays silent may have failed, or it may never be getting the signal to run.

If you hear the pump running and water moving, yet the tub never empties all the way or a little dirty water keeps coming back, suspect the check valve flapper. Stuck open, it lets drained water flow back in. Stuck shut, it gives the pump nothing to push through, and a good pump looks dead.

Our technician clears the drain path end to end first, then pulls the drain pump to check the impeller for debris and tests the motor and the power reaching it on the drain step. We look at the check valve while the pump is out.

What it usually turns out to be

Cleaning or upkeepClogged filterThe filter under the bottom rack catches food before it reaches the pump. Packed full, it holds water in the tub, and you can usually see scraps and grit sitting on it.
Cleaning or upkeepKnockout plug in a new garbage disposalA new disposal comes with a plug in its dishwasher inlet that has to be knocked out when it's installed. If the draining trouble started right after a disposal went in, that plug is the likely cause.
Cleaning or upkeepClogged air gap or kinked drain hoseWater spitting out of the air gap beside the faucet, or backing up into the sink when the dishwasher drains, means the air gap or the hose past it is restricted. The pump is working; the path is blocked.
PartDrain pumpThe pump pushes the water out at the end of each cycle and can jam on broken glass or a fruit pit. A pump that hums but moves no water is usually jammed rather than burned out.
PartDrain check valveA one-way flapper stops drained water from flowing back into the tub. If you hear the pump running but the tub never empties, or a little dirty water keeps coming back, the flapper is likely stuck.

Try this first

Lift out the bottom rack, remove the filter and rinse it under the tap until the mesh is clear.
If it drains through the garbage disposal, run the disposal first, and if the disposal is new, make sure its dishwasher knockout plug was removed.
If your sink has an air gap (the small cap beside the faucet), lift the cap off and clear out any food packed inside.
Under the sink, check that the drain hose isn't kinked or crushed by anything stored there.

Stop using it and call now if

Water coming through the floor or into the cabinets
A glass broke in the tub and the pump now hums or grinds (don't reach into the sump)
A burning smell

Call (636) 367-1968

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