The short answer
A countertop machine drains over a sink edge, so the height the hose hangs at is part of the appliance. Ranked first on this platform: The drain hose height at the sink. The checks below follow that ranking, and the first of them need no tools and no panel removed.
What you observe
- Behaviour changes depending on where the machine is standing — A fault that moves with the machine is about the installation, not the machine.
- Standing water above the filter at the end of every cycle — Water sitting on top of the filter names the blockage.
- A hum from the base with no water moving at all — Hum without flow is a stalled impeller.
- NEAR MISS — it drains but leaves dishes dirty — That is a wash-performance question and it is diagnosed from the filter and the arms rather than from the drain.
Causes, most likely first on this platform
- The drain hose height at the sink — A portable machine drains over a sink edge, so the height it hangs at decides everything: too high and the pump cannot lift the water, too low and the machine siphons itself empty as it fills. It ranks first on this platform because too high and the pump cannot lift the water, too low and the machine siphons itself empty as it fills — and because the hose is rehung every time the machine is moved, the fault appears and disappears with the installation.
- A blocked filter and sump — Everything the machine washes off ends up in the sump, and the filter is what holds it there. It ranks second here because the drain hose hooks over a sink edge rather than joining a waste trap, so its height and its kinks are set by wherever the machine happens to be standing.
- Something jammed in the pump — Glass, a fruit stone or a bone fragment reaching the impeller stops it dead. The pump hums and moves nothing, and repeating the attempt only heats the motor. Ranked third: worth checking once the causes above have come back clean.
- The household drain — The machine pumps into the same waste as the sink. If that is partly blocked the water comes back, and the evidence is usually visible at the sink rather than at the appliance. It ranks fourth rather than higher: real on this platform, and less common than the causes above it.
Check in this order, and why
- Look at where the hose end sits relative to the machine — It is the variable unique to this class of machine. It leads because it tests the top-ranked cause.
- Lift the filter out and look into the sump below it — Free, immediate, and it is the leading cause. Tests the second-ranked cause.
- Clear the sump and look into the pump inlet with a torch — Power off, glove on, and look before reaching. Tests the third-ranked cause.
What an owner can safely check
- Hook the hose over the sink edge at the height the instructions give and secure it — Secure it: a hose that falls into the bowl siphons.
Tools: cable tieAbout 15 min
- Bail the water out, twist out the filter, and clear the sump by hand — Glove on: broken glass in a sump is common.
Tools: jug, glove, clothAbout 25 min
- STOP before anything behind a fixed panel, and note what each check showed — Everything past this line is measured rather than looked at, and measuring it safely needs the power off and a meter.
Before you open anything
Safety
Unplug the machine or switch off its breaker before removing any panel, and close the supply valve before disturbing a fitting. Broken glass in a sump is common: wear a glove and look before you reach.
When to call a technician
Call when the filter, the hose and the household drain are all clear and the machine still will not empty, because what is left is the pump or the control.
Nearest pages of this class
What this page does not cover
This page is written for the MooSoo dishwasher as a class, not for one family or one model line. Where a family- or model-specific page exists for your unit, that page is the more specific answer and the one to read first. Deliberately not here: part numbers, wiring colours and disassembly order, which differ by family.
Lead Appliance Repair Technician · 12 years experience
Experienced technician with 12 years specializing in washing machine and dryer repairs across all major brands.
