Asko Dishwasher: Will Not Drain
Standing water in the bottom of a dishwasher is almost always a blockage rather than a failed pump, and the blockage is usually in one of three places you can reach: the filter assembly in the sump, the drain hose behind the machine, or the air gap or waste connection under the sink. Asko is a Scandinavian premium brand: heavier build, stainless interiors, machines designed for long life and quiet running. Clearing the filter, the hose and the waste connection is owner work and it ends most of these. Replacing a pump is not.
What the owner actually observes
- Water stands in the sump above the filter at the end of the cycle.
- The machine hums at the drain step but the level does not fall.
- Water drains slowly and the last of it never leaves.
- Dirty water appears in the sump after the sink has been used.
- The cycle stops partway and reports a fault with water still in the machine.
- Not this fault: If the machine is draining but dishes are coming out dirty, the wash arms and the filters are the place to look. That is a different fault — see Asko Dishwasher: Does Not Clean or Dry (asko-dishwasher-cleaning-performance).
- Not this fault: If water is on the kitchen floor rather than in the sump, that is a leak instead. That is a different fault — see Asko Dishwasher: Water Leak (asko-dishwasher-water-leak).
Ranked for an Asko dishwasher
- Deferred maintenance and water quality — scale, residue and clogged screens — Rank: first — Why ranked here: it ranks where it does because a machine built to last outlives its consumables by a wide margin, so on any Asko with years of service the accumulated residue is a more likely cause than the components themselves
- A blocked filter assembly in the sump — Rank: second — Why ranked here: it ranks where it does because the filter is designed to be removed and rinsed by the owner, because food debris and grease build there faster than anywhere else, and because on a machine that has never had it cleaned it is blocked far more often than not
- The waste connection under the sink — a blocked spigot, air gap or disposer inlet — Rank: third — Why ranked here: a dishwasher discharges into the sink waste, and the spigot it connects to is frequently left with its knock-out plug still in place after installation or blocked with grease from the sink above it
- The filter refitted incorrectly after cleaning — Rank: fourth — Why ranked here: a filter that is not locked home lets debris bypass it straight into the pump, so a drainage fault appearing shortly after a cleaning session usually has a simple explanation
- The drain hose kinked, crushed or without a high loop — Rank: fifth — Why ranked here: the hose runs behind the machine where it is crushed when the appliance is pushed into its housing, and a hose without the required high loop lets waste water siphon back into the tub
- An object jammed in the drain pump impeller — Rank: sixth — Why ranked here: glass fragments, olive stones and labels from jars pass the filter when it is not seated correctly and stop the impeller, which produces a hum without flow
- Note: Because these machines are built heavier and quieter than average, the order below puts consumables, water quality and maintenance first, and structural or mechanical failure last: on a machine built this way, the odds move away from the metal and toward what passes through it.
Check in this order
- The filter assembly in the base of the tub, unscrewed and lifted out — Order: first — Because: it is free, it is designed for owner access, and it is the most likely single finding
- The connection under the sink, the air gap if one is fitted, and the disposer inlet if the machine drains through one — Order: second — Because: the whole thing is outside the appliance and it explains a machine that has never drained properly since the day it was fitted
- The hose behind the machine for kinks and crushing, and whether it rises in a high loop before dropping to the waste — Order: third — Because: it explains both a machine that will not drain and one that fills with dirty water on its own
Owner-safe checks
- Look at what the machine has been consuming rather than what it is made of. Check filters, seals and screens for the residue of hard water and detergent, and check that the maintenance the machine expects has actually been done — on a heavily built machine, that is where the fault usually is. — Step: first — Tools: a torch and a phone camera — Time estimate: a few minutes
- Bail the standing water out into a bowl with a cup and a sponge until the sump is dry enough to work in. Everything below is easier and cleaner once the basin is empty. — Step: second — Tools: a cup, a sponge, a bowl — Time estimate: under a quarter of an hour
- Unscrew and lift out the filter assembly, rinse every part of it under a tap with a brush until the mesh is genuinely clear, and clean the sump beneath it. Refit it so it locks positively home. — Step: third — Tools: a brush, warm water — Time estimate: under a quarter of an hour
- Look under the sink at the waste connection: check the air gap if one is fitted, check the hose is not kinked, and confirm the spigot is not blocked. If a disposer is fitted, run it and check its inlet plug was removed. — Step: fourth — Tools: a torch, a bucket — Time estimate: under a quarter of an hour
- Pull the machine forward far enough to see the drain hose run, check for crushing behind the cabinet, and confirm the hose rises in a high loop before it drops to the waste. — Step: fifth — Tools: a torch — Time estimate: under a quarter of an hour
- Clear every filter and screen the machine has, and check whether the water it runs in is hard: scale and detergent residue collect on the surfaces that matter most and produce symptoms that mimic component failure. Then run one cycle and reassess before opening anything. — Step: sixth — Tools: a soft brush, white vinegar or a descaler, a torch — Time estimate: under a quarter of an hour, plus a cycle
- Stop condition: Stop before removing the drain pump or the sump housing; that means pulling the machine out and working under it with the water and power connected.
Safety
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 dishwasher sump can contain broken glass and hot water, and the machine is connected to both mains water and mains electricity under a worktop. Wear gloves when clearing a sump, since broken glass is the most common thing found in a dishwasher filter. Switch the machine off at its isolating switch or breaker before reaching into the sump. Wear gloves when clearing a sump, since broken glass is the most common thing found in a dishwasher filter. Switch the machine off at its isolating switch or breaker before reaching into the sump. unplug-before-service
When to call a technician
The line is anything past the filter, the hose and the waste connection. Call if the pump is silent at the drain step, which points at the pump or its wiring. Call if the filter, hose and waste connection are all clear and water still stands. Call if dirty water appears in the tub after using the sink, which suggests the high loop or the waste arrangement. Call if the machine will not drain and the door has locked with water inside.
Nearest pages of the same kind
What this page does not cover
This page is generalized across every family and model sold under the Asko badge. It does not carry model-specific error-code tables, family-specific service procedures, sealed-system work or parts numbers, and no model-specific page exists beneath it yet — the data plate on your unit is the authority, not this page. For the other faults on this appliance, start from Common Asko Dishwasher Problems (asko-dishwasher-problems) and pick the symptom that matches.
Links: - [Common Asko Dishwasher Problems](/blog/asko-dishwasher-problems) - [Asko Dishwasher: Abnormal Noise or Vibration](/blog/asko-dishwasher-abnormal-noise) - [Asko Dishwasher: Does Not Clean or Dry](/blog/asko-dishwasher-cleaning-performance) - [Asko Dishwasher: Controls, Display or Error Code](/blog/asko-dishwasher-control-fault) - [Asko Dishwasher: Cycle Will Not Run or Complete](/blog/asko-dishwasher-cycle-fault)
Lead Appliance Repair Technician · 12 years experience
Experienced technician with 12 years specializing in washing machine and dryer repairs across all major brands.
