The short answer first
On a Maytag dishwasher, a tub left full of water is most often a blocked air gap or a disposer knockout left in rather than a clogged filter and sump screen. The mechanical and blockage causes come first, because on a platform this common the pattern is known: the parts that move and the parts that carry water. All three checks below are owner work, and not one of them needs a part.
What you observe
- It drains, but far more slowly than it used to — A gradual slowing is the filter loading rather than a sudden blockage.
- A hum during the drain phase with nothing leaving — The pump is being asked to work and cannot move water.
- A smell from the tub between cycles — Standing water and trapped food do this within a day or two.
- NEAR MISS — it drains but the dishes are dirty — A machine that empties properly but cleans badly is a different fault entirely.
Why this happens, likeliest first
- A blocked air gap or a disposer knockout left in — Where the drain runs through an air gap on the sink, that fitting blocks with debris. Where it runs into a food disposer, a knockout plug left in place at installation blocks it completely from the first day. It leads because the connection outside the machine is the part nobody thinks to look at. It is a fitted kitchen appliance, plumbed and levelled when the kitchen was built and rarely touched since.
- A drain hose with no high loop, so waste water siphons back — The hose needs a rise in it before it reaches the waste connection. Without one — or trapped flat behind the machine — water runs back into the tub, and the fault starts the day the machine was last moved. It sits here because the hose run is felt by hand in a minute.
- A clogged filter and sump screen — A dishwasher recirculates its water many times in a cycle, so the filter works constantly rather than once. It loads far faster than owners expect, and it is the first restriction the water meets on the way out. It is last only because the filter was cleared recently.
Check in this order, and why
- Lift the cap off the air gap on the sink and look inside — Debris in the air gap blocks the drain as completely as anything in the machine. First, because it is the likeliest to end the job.
- Feel along the hose where it passes behind the machine — A flattened hose is easy to feel and almost impossible to see. Second, once that is clean.
- Twist out the filter in the base of the tub and look at the mesh — A film you can see through is fine; a mat of debris is the fault. Third, and by now the answer is usually in hand.
The steps, with tools and times
- Clean out the air gap, or have the disposer knockout removed — A knockout left in at installation blocks the drain from day one.
Tools: clothAbout 20 min
- Free the hose and secure a high loop under the worktop — Use the clip the machine came with, or a cable tie to the cabinet wall.
Tools: cable tieAbout 20 min
- Bail the standing water out, then clear the filter and sump by hand — Jug, cloth and a glove — broken glass in a sump is common.
Tools: jug, cloth, gloveAbout 25 min
- STOP — note whether the pump hums or stays silent — That one observation shortens the visit and often decides which part is ordered.
The part that is not optional
Safety
Unplug the appliance or switch off its breaker before removing any panel. A capacitor can hold a charge after the power is off. Close the water supply valve under the sink before opening any fitting — water arriving under pressure into a cupboard does more damage in an hour than the repair costs.
Where the owner fix ends
Call when the filter, the sump, the hose and the air gap are all clear and the pump still hums without moving water, or when the machine is silent through the drain phase. A blocked household waste line is a plumber rather than an appliance call. On this brand parts are available, documented and priced sensibly, so the repair-or-replace question usually answers itself in favour of repair.
The closest pages to this one
Generalized information
This page is written for the appliance class, not for one Maytag model line. Where a family- or model-specific page exists it is the better answer and it is linked below — go there first if your model is named. Not here: filter shapes, pump variants, hose routing, or part numbers.
Lead Appliance Repair Technician · 12 years experience
Experienced technician with 12 years specializing in washing machine and dryer repairs across all major brands.
