The short answer
On a Vissani dishwasher the ranking below is the answer, and it is not the generic one. Most likely here — The disposal knockout plug still in place. Least likely, and a service call from the first minute — A failed drain pump. The checks at the top of the list cost nothing and need no panel off.
What you actually observe
- Water standing in the tub at the end of the cycle — The clearest version of this fault.
- A hum during the drain step with nothing moving — Blocked path or failed pump.
- It drains slowly and leaves a shallow pool — A restriction rather than a blockage.
- NEAR MISS: a little clean water always sits in the sump — That is normal on most machines and keeps the seals wet.
Causes, most likely first on this build
- The disposal knockout plug still in place — When a dishwasher is plumbed into a new waste disposal, a moulded plug has to be knocked out first. Left in, the machine can never drain at all, and it is always the cause on a newly installed machine. Ranked first on a Vissani: a cabinet in a garage or a basement lives in air that swings further than any kitchen's, and that swing is the biggest single influence on it.
- A blocked filter and sump — The filter and the sump beneath it collect everything the load carries in. Second here, because a house-badge cabinet is built to a retail price, so the seal and the fan are the parts with the least margin in them.
- A check valve holding shut — The valve stops waste water returning to the tub. Third, once the two above are clean: it is free to check and it explains most of what a secondary unit is blamed for.
- A failed drain pump — A pump that has jammed or burned out gives a hum, or silence, with no water moving. Last, and the reason the order above matters: it is the rarest cause, and at this price point it is the one that turns a repair into a replacement decision.
Check in this order, and why
- Ask whether the disposal is new — A machine that has never drained has never had the plug out.
- Lift the filter out and look into the sump — Owner-serviceable and usually full.
- Note whether water returns to the tub after a cycle — Water coming back is a valve story.
What an owner can safely check
- Check the hot supply actually arrives hot at the machine rather than at the tap — A house-badge machine is usually installed on whatever run of pipe was already there.
About 10 min
- Bail out the standing water, then lift the filter out and clear the sump underneath — Expect debris. This is designed as owner maintenance and it is the commonest single cause.
Tools: a cup, a cloth, a soft brushAbout 25 min
- Lift the cover off the air gap on the worktop, if there is one, and clear it — A packed air gap blocks the drain completely and takes a minute to clear.
About 10 min
- STOP HERE if the pump hums with the filter, hose and air gap all clear — That is where an owner check ends and a service call begins.
Before you open anything
Safety
Switch the machine off at the isolating switch under the worktop, or unplug it, before opening any panel, and shut the supply valve under the sink. A capacitor can hold a charge after the power is off.
When to call a technician
Call when the filter and sump are clear, the air gap is clear, the hose has no kink and the knockout plug is accounted for, and the machine still holds water. A pump or a check valve means pulling the machine out of its space, and that is where the owner's part ends.
Where to go next in this class
What is deliberately not on this page
This page is written for the Vissani dishwasher as a class, not for one family or model line. Where a family- or model-specific page exists for your machine it is linked above, and it is the more specific answer.
Lead Appliance Repair Technician · 12 years experience
Experienced technician with 12 years specializing in washing machine and dryer repairs across all major brands.
