Clean the filter first — it solves this more often than every other cause combined. Water left standing at the bottom of a dishwasher after the cycle finishes means the drain pump could not clear it, and a blocked filter starving the pump is by far the most common reason. Kinked drain hoses and a garbage disposal knockout plug that was never removed come next.
Why water gets left behind
At the end of every wash and rinse phase, the dishwasher pumps dirty water out through the filter and drain hose before bringing in fresh water for the next phase. If anything restricts that path — a blocked filter, a kinked hose, an obstruction downstream — the pump cannot fully clear the tub, and you find water pooled around the filter housing when you open the door.
Common causes
| Cause | How likely | Typical sign |
|---|---|---|
| Blocked filter assembly | Very common | Visible debris in the filter mesh; pump audibly straining |
| Kinked or crushed drain hose | Common | Hose pinched behind the machine after installation |
| Garbage disposal knockout plug not removed | Common | New machine, or newly connected to a disposal unit |
| Blocked air gap or high loop | Common | Water backing up from the sink side |
| Clogged drain hose | Occasional | Gradual worsening over several cycles |
| Failed drain pump or check valve | Occasional | Little or no pump sound at the drain phase |
| Kitchen sink drain blocked | Occasional | Sink also draining slowly |
How to fix it
Switch off at the wall before removing the filter. Bail out any standing water with a cup and cloth first — it is easier to work in a dry tub, and the water will be greasy.
- Remove and clean the filter assembly
Twist the inner fine filter and lift the outer coarse mesh out — most machines make both removable without tools. Rinse thoroughly under a hot tap and scrub with an old toothbrush until no film remains. Check the recess underneath for anything trapped, such as a piece of broken glass or a label.
- Check the drain hose for kinks
Pull the machine out and follow the hose from the base of the machine to where it connects at the sink or waste pipe. A hose crushed when the machine was pushed back into its cabinet restricts flow enough to leave water behind every time.
- Confirm the high loop or air gap
The drain hose should rise to its highest point — usually clipped under the worktop — before dropping down to the connection point. This stops water siphoning back from the sink drain into the dishwasher. If the hose runs low the whole way, that is worth correcting.
- Check the connection point is clear
Whether the hose joins a dedicated stub on the sink’s waste pipe or an air gap fitting on the countertop, that connection point can itself clog with food debris. Detach it if you can and check for blockage.
- Test with an empty cycle
Run a rinse-only cycle with the tub empty and watch the base at the end. If it is dry, you have solved it. If water remains but noticeably less than before, you have improved flow but not fully cleared the obstruction — repeat the filter and hose checks.
A drain pump that runs loudly and continuously without clearing the water is fighting a blockage. A pump that is completely silent when it should be running points instead at the pump itself or its wiring — a different, less common problem.
The garbage disposal connection
If your dishwasher drains into a garbage disposal unit, there is a knockout plug inside the disposal’s dishwasher inlet that must be removed before the first use. It is very easy for an installer to miss, and the symptom is exactly this — water that never leaves the dishwasher at all, because the drain hose is plumbed into a dead end.
If the machine has always struggled to drain since it was installed or since the disposal unit was fitted or replaced, check this before anything else. It is inside the disposal unit itself, not the dishwasher, and the disposal’s own manual shows exactly where.
When to call a professional
Call a plumber if the kitchen sink itself is draining slowly, since a shared blockage downstream will affect the dishwasher too. Call an appliance engineer if the filter and hoses are clear, the connection point is open, and the pump is silent or straining without clearing the water — that points at the pump or the check valve inside it, which sit behind the water inlet and need the machine partially dismantled.
Stop and call a qualified appliance technician or electrician if you find scorched or melted wiring, smell burning, see water that has reached electrical components, or if the fault returns immediately after a repair. Never bypass a safety device — thermal fuses, door interlocks and flood switches fail for a reason, and defeating one converts a broken appliance into a fire or flood risk.
