The short answer
On a portable machine the drain is a hose over the sink, and that is where the fault nearly always is: slipped, kinked, sitting too low or discharging into a full sink. Check the hose before opening anything.
What you actually see and hear
- Water standing above the filter at the end of the cycle — The machine could not pump it out, or it came back in.
- Water in the sink rising while the machine pumps — The sink drain is slow, so the machine has nowhere to go.
- The hose has slipped out of the sink — Obvious once you look, and the commonest cause of a mess as well as a fault.
- It drains and then refills itself — A siphon, because the hose end is sitting below the water level.
- NEAR MISS - a little water always left in the sump — Normal, and deliberate, to keep the seals from drying.
Causes, most likely first on this machine
- Drain hose position and routing — First and by a wide margin. Over the sink rim with a proper rise, secured so it cannot slip - anything else produces exactly these symptoms.
- A kinked hose behind the machine — Second. Wheeling a portable back against a wall kinks the hose at the connector nearly every time.
- A full or slow sink — Third. The sink is the machine's drain, and if it is blocked or full of washing-up water the machine cannot empty.
- Blocked filter and sump — Fourth, and the first thing inside the machine: small filters fill fast.
- Drain pump or check valve — Last. Pumps do fail, but they are outlived by the hose arrangement in front of them.
Check in this order, and why
- Look at the hose before touching anything else — Position, rise, kinks and whether the sink is clear. That is most of the diagnosis.
- Empty the sink and run a drain cycle — Removes the simplest cause in a minute.
- Check the hose end is above the water level in the sink — Below it, the machine siphons and refills itself.
- Pull and clean the filter — The most likely internal cause and an easy one.
What an owner can safely check
- Bail the standing water out with a jug and a sponge — Do it first so you can see the filter and work.
Tools: jug, sponge, towelsAbout 15 min
- Reposition the drain hose over the sink rim and secure it — It must rise before it falls, and it must not be able to slip.
About 10 min
- Straighten the hose behind the machine — Kinks appear every time a portable is pushed back into place.
About 10 min
- Empty the sink and clear its plughole and trap — The machine cannot drain into a sink that is not draining.
Tools: bucketAbout 20 min
- Remove and clean the filter and clear the sump — Wear a glove for glass chips.
Tools: gloves, brushAbout 20 min
- STOP HERE before removing the pump or opening the sump housing — Wet work near live terminals and the least likely cause.
Before you open anything
Safety
Unplug the appliance or switch off its breaker before removing any panel - a capacitor can hold a charge after the power is off. A portable dishwasher puts a live appliance, a mains socket and a hose full of water in the same small space, so switch off at the breaker before moving it or touching a connection. Disconnect the tap adapter before wheeling the machine, and never leave it connected to a live tap while it is unattended.
When to call a technician
Call when the hose is correctly routed and secured, the sink drains freely, the filter is clean and the machine still holds water - that leaves the pump or the check valve. Call a plumber instead if the sink itself is slow, because you have one blockage showing up as two problems. If the machine has never drained since it was bought, check the hose routing against the instructions before calling anyone: a portable that was set up wrong has never had a chance.
Nearest pages of this class
What this page does not cover
This page is written for the freestanding portable dishwasher class, not for one family or model line. Where a brand- or model-specific page exists for your unit it is the more specific answer and it is linked above, so go there first if your machine is named. What is deliberately not here: spray arm and pump part numbers, adapter thread sizes, hose specifications and control diagnostics, all of which differ by family and belong on the page for that family.
Lead Appliance Repair Technician · 12 years experience
Experienced technician with 12 years specializing in washing machine and dryer repairs across all major brands.
