Washing Machine Overfilling
A washing machine overfilling is most commonly caused by a blockage in the pressure chamber – a build-up of grease and residue that prevents the pressure system from detecting when the correct water level has been reached. If water continues entering after the machine is switched off, the inlet valve has jammed open and the water supply must be turned off immediately at the tap.
Turn off the water supply at the isolation tap immediately. A jammed inlet valve will not stop filling regardless of the machine’s controls. Do not attempt to investigate the machine until the water supply is isolated.
An overfilling washing machine may be obvious – water visible at the top of the door glass, spilling from the soap drawer, or running from the back of the machine. But many modern machines detect overfilling automatically, abort the cycle, and pump the water out before any visible flooding occurs. In those cases the only sign is a cycle that starts to fill and then unexpectedly stops and drains.
If the machine is producing excessive foam rather than overfilling with plain water, see our guide on too much foam in the washing machine instead.
First: Does the Filling Stop When You Switch the Machine Off?
This single check immediately separates two very different faults.
Water stops when machine is switched offThe inlet valve is working correctly. The fault is within the pressure system that tells the machine when to stop filling. This is the more common cause.
Water continues when machine is switched offThe inlet valve is jammed open. Turn off the water supply at the tap immediately. A new inlet valve will be needed – the machine cannot control filling until it is replaced.
The Most Common Cause: A Blocked Pressure Chamber
When the filling stops after the machine is switched off, the fault is almost always in the pressure system. Washing machines use a pressure chamber – a small sealed chamber at the base of the drum – connected by a thin hose to a pressure switch. As water rises in the drum, air is compressed in the chamber and hose, and the rising pressure triggers the switch to cut off the water supply at the correct level.
Over time, grease and detergent residue can build up inside the pressure chamber, partially or fully blocking it. When blocked, air pressure cannot rise correctly, the pressure switch never receives the signal to stop filling, and the machine continues taking in water beyond the normal level.
Clearing a blocked pressure chamber is a possible DIY repair for those with some appliance experience. See our guide on clearing a blocked pressure system for more detail. For a fuller explanation of how the pressure system works and the range of faults it can cause, see our guides on how washing machines control water levels and faults on pressure systems.
Other Overfilling Causes to Be Aware Of
A blocked pressure chamber is the most likely cause, but it is not the only one. Other faults in the pressure system – including a failed pressure switch, a split or disconnected pressure hose, or a faulty control board that is not correctly processing the pressure switch signal – can produce the same symptom. These require more investigation and in most cases the input of a qualified engineer.
Related Faults With Similar Symptoms
Two related faults are sometimes confused with a genuine overfilling problem.
Machine Fills and Drains at the Same Time
If water appears to be entering the machine but also running straight down the drain, so that the drum never seems to fill properly, this is a distinct fault caused by syphoning rather than overfilling. See our guide on washing machine fills and drains at the same time.
Machine Fills With Water When Switched Off
If water slowly enters the drum even when the machine is not running and completely switched off, this is caused by a leaking or partially jammed inlet valve – different from a valve jammed fully open during a cycle. See our guide on washing machine fills with water when switched off.
Need a Qualified Engineer?
Pressure system faults and valve replacements are straightforward for an experienced engineer. Whitegoods Help can connect you with a vetted repair company.
Related Guides
How Washing Machines Control Water LevelsA full explanation of the pressure system – how it works, what it controls, and why it is the most common source of overfilling faults.
Faults on Pressure SystemsThe full range of faults that can occur within the pressure system – including symptoms, causes, and what is involved in repair.
Washing Machine Fills and Drains at the Same TimeA related fault where water enters and drains simultaneously – caused by syphoning rather than a pressure system fault.
Washing Machine LeakingIf the overfilling has caused water to escape, this guide covers the most common leak points and their causes.
Frequently Asked Questions
Why is my washing machine overfilling with water?
The most common cause is a blockage in the pressure chamber – a build-up of grease and residue that prevents the pressure system from detecting when the correct water level has been reached. Less commonly, the fault may be a failed pressure switch, a split pressure hose, or a faulty control board. If water continues entering after the machine is switched off, the inlet valve has jammed open and the water supply must be turned off immediately.
How do I know if the problem is the inlet valve or the pressure system?
Switch the machine off. If the water stops entering immediately, the inlet valve is working correctly and the fault is in the pressure system. If water continues to flow in with the machine switched off, the inlet valve has jammed open and will need replacing.
What should I do if my washing machine is overflowing?
Turn off the water supply at the isolation tap behind or beside the machine. If the machine is still running and pumping, let it finish pumping out the water before investigating further. Once the water supply is isolated and the drum is empty, the machine is safe to leave until it can be repaired.
Can I fix an overfilling washing machine myself?
If the cause is a blocked pressure chamber, clearing it is a possible DIY repair for those with some appliance experience. Other pressure system faults – a failed switch, split hose, or control board issue – are more involved and in most cases better left to a qualified engineer. Replacing a jammed inlet valve is within the scope of a competent DIY repairer but does require isolating the water supply and basic plumbing confidence.
My washing machine fills then immediately drains without washing – is that overfilling?
Not necessarily. If the machine detects overfilling, it may abort and drain as a safety response – in which case overfilling is the cause. But a machine that fills and drains without washing can also be caused by a heating fault (the water never reached temperature) or by syphoning through the drain hose. Check our guides on washing machine stops mid-cycle and washing machine fills and drains at the same time for more detail.
2 Comments
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0 replies I have an article for that here Matt - Washing machine fills with water when off
0 replies My washing machine still keeps filling up with water when its turned off can u help
My washing machine still keeps filling up with water when its turned off can u help
I have an article for that here Matt – Washing machine fills with water when off