Dishwasher not draining? The five checks before you call anyone

Opening the dishwasher to a inch of yesterday's water is a grim moment, but it is usually a twenty-minute fix with a towel and a torch. Work the checks in order - they run from most-likely-and-free to call-a-technician.

The five checks, in order

1. The filter. The basket in the floor of the machine is the number one cause: twist it out, rinse it under a hot tap with an old toothbrush, and be honest about how long it has been - a filter clogged past recognition slows drainage for weeks before it stops it. This is a monthly habit, not an emergency move (the same discipline as the machine's other consumables - loading it right prevents half of these clogs in the first place, and the vinegar clean handles the grease film a filter cannot reach).

2. The drain hose. Pull the machine out enough to see the corrugated hose running to the sink plumbing: kinks happen when a machine is pushed back after cleaning. Straighten it and run a rinse cycle.

3. The sink side. If the sink drains slowly too, the blockage is downstream of both - the sink trap or the standpipe, not the dishwasher. Clear the sink first (the machine often "recovers" instantly once its exit is open). If the machine drains into a waste disposal, run the disposal fully first - a blocked disposal backs the dishwasher up, and on a brand-new installation check the metal knockout plug inside the disposal's inlet was actually knocked out: it is the classic "new dishwasher doesn't drain at all" cause.

4. The air gap or high loop. Some installs have a small cylinder beside the tap (the air gap) that clogs with debris - unscrew the cap and rinse it. Installations without one rely on the drain hose looping high under the sink; a hose that has sagged lets sink water flow back in, which looks exactly like a drainage failure.

5. Listen at the end of a cycle. A hum with no drain action, grinding, or clicking-then-nothing points at the drain pump - genuinely a technician's part. Note the sound and the cycle stage; that description is worth more than the model number when booking.

While the water is standing

Scoop or towel out the worst rather than running another cycle over it, and skip the temptation to chemical-flood the machine with harsh drain unblockers - they sit in the sump with your dishes' next cycle. And keep perspective on urgency: a dishwasher standing full is an inconvenience, not a flood - the same cannot be said of its sibling failure, a washer that will not drain mid-cycle, where the water volume is ten times bigger. When the machine is old and the pump is the verdict, that is exactly the moment for the repair-or-replace arithmetic - pump repairs on a fifteen-year-old machine rarely make sense.

Twenty minutes, in order, and the machine either runs clean again for free or you hand the technician a one-line diagnosis instead of a mystery.