Dishwasher Not Draining? Fix It in Six Steps

Standing water at the end of a cycle is the most common dishwasher fault there is, and it is also the one most likely to be solved in twenty minutes with a towel and a screwdriver.

This is the order a technician works through it. Follow it and you will either fix the problem or know exactly what to tell whoever you call.

Before you start: turn the dishwasher off at the wall or the breaker. You will have your hands inside a machine that expects to be able to start a pump.

Step 1 — Bail out the standing water

You cannot inspect anything through several centimetres of dirty water.

Lay towels down, then scoop the water out with a cup into a bucket. The last of it comes up with a sponge or a wet-vac if you have one. It is unpleasant for about four minutes and it makes everything after this straightforward.

Step 2 — Clean the filter assembly

This is the fix about half the time. The filter sits in the base of the tub, usually as a cylindrical part you twist and lift out, sometimes with a flat mesh screen beneath it.

Take both out. Rinse under a hot tap, use a soft brush on the mesh, and clear anything caught in the housing they sit in. What comes out is typically food debris, seeds, labels from jars and — often — fragments of glass.

Refit firmly. A filter that is not locked down properly lets debris straight through to the pump, which turns a cheap problem into a more expensive one.

Run a short cycle. If the water drains, you are done.

Step 3 — Check the drain hose

Behind or under the machine, the drain hose runs to the sink trap or the garbage disposal.

Look for a kink — hoses get crushed when a dishwasher is pushed back into place after servicing or a kitchen change. Straighten anything obvious.

Then check the high-loop. The hose should rise up under the countertop before descending to the drain connection. That loop stops waste water flowing back into the machine. If the hose runs straight along the floor, that is an installation fault, and it is one of the most common things we find in newer homes — the machine has been draining badly since the day it was fitted.

Step 4 — Check the disposal and the air gap

If your dishwasher drains into a garbage disposal:

• Run the disposal. A partial blockage there stops the dishwasher draining too.
• Check the knockout plug. New disposals ship with a plug sealing the dishwasher inlet, and it has to be removed during installation. If it was missed, the dishwasher cannot drain at all — and it presents exactly like a failed pump. This catches people constantly in new builds.

If you have an air gap — the small chrome cylinder on the sink deck — lift the cover and clean it out. They block with debris and stop drainage completely.

Step 5 — Look at the sink trap

The dishwasher drains into the same plumbing as your sink. If the sink is slow, the dishwasher will be too.

Run the tap. If the sink drains sluggishly, the trap is your problem rather than the appliance, and clearing it fixes both.

Step 6 — Check the drain pump

This is the last step you can do yourself, and only on machines where the pump is accessible from inside the tub after removing the filter and a cover plate. Check your manual; on some models it is not reachable without pulling the machine.

With the power off, look for anything jamming the impeller. Glass fragments are the usual culprit and the reason we recommend checking the sump after anything breaks in the machine.

Be careful. Broken glass in a pump housing is exactly as sharp as it sounds. Gloves.

If the impeller is chipped or scored, cleaning it is not enough — a damaged impeller moves water badly and the fault returns within weeks.

Error codes worth decoding

E24 versus E25 is the distinction worth remembering: the first is often yours to fix, the second is generally not.

When to call a pro

Stop and call if:

• The filter, hose, disposal and trap are all clear and it still will not drain
• The pump hums but moves no water — it is jammed or failed
• You see E15 or any leak warning. Water has reached the base pan, and in a condo that becomes your neighbour’s ceiling before it becomes your problem
• The impeller is visibly damaged
• There is water under the machine as well as in it

A drain repair is one of the less expensive things we do. The service call is $120 plus HST and covers the full diagnosis, you approve a written quote before any work, and the repair carries a 60-day parts and labour warranty.

What we would genuinely rather you did first is Step 2. We talk people through it on the phone several times a week, and when it works nobody pays for a visit — which is how it should be.

More detail on symptoms and what a visit involves is on our dishwasher repair page, and there is a real Square One job where the filter was clean and the pump was not.