Why is my dishwasher not filling with water?
Water, valve, filter, float — four things in a short line, and three of them are owner-checkable in twenty minutes.
- Difficulty
- beginner
- Time
- 30 min
- Read
- 4 min
- Safety
- caution
Short answer
Check the isolating valve is actually open, then check the small filter gauze inside the inlet hose union at the machine end — a blocked gauze is the most common cause and it costs nothing. If the machine hums but no water arrives with the supply open and the gauze clear, it is the inlet valve, which is an engineer's job.
A dishwasher that starts, hums and then errors is usually being starved of water rather than failing electrically. The supply route is short: isolating valve, hose, a fine gauze filter in the union, the machine's solenoid inlet valve, and a float or pressure sensor that tells the machine when there is enough water. Working along it in order settles it quickly.
Safety
What you'll need
- A bowl and towels
- An adjustable spanner or pliers
- A torch (optional)
- A pin or fine brush (optional)
Step by step
- Check the isolating valve under the sink is open.The lever should lie along the pipe, not across it. Screwdriver-slot valves have the slot along the pipe when open. This gets knocked when things are stored under the sink and it is a genuinely common cause.
- Check the rest of the house has water.Run the kitchen cold tap. A supply interruption, a stopcock partly closed after other work, or a frozen pipe in winter all show up here first.
- Switch off at the socket and close the isolating valve.Before disconnecting anything. Have a bowl ready — the hose holds water.
- Undo the inlet hose at the machine end and check the gauze filter.Inside the union there is a fine mesh disc. It catches grit and rust from the supply and blocks solid over the years. Pick it out carefully, rinse it, brush it, and put it back the same way round. This is the single most common fixable cause.
- Check the hose is not kinked behind the machine.A machine pushed back hard against the wall can flatten its own inlet hose against a pipe or a skirting. Pull it out and look.
- Check whether an AquaStop hose has tripped.Hoses with a bulky plastic head at the tap end contain a mechanical shut-off that latches closed after a surge. Some reset when the supply is turned off and back on; many are one-shot and need replacing. A red indicator window on the head usually shows it.
- Check the base tray float has not tripped.Many machines refuse to fill if there is water in the base tray, because filling further would make a leak worse. If the machine has recently leaked, this is your answer, and the leak needs finding before anything else.
- Listen at the moment it should fill.Reconnect, open the valve, switch on and start a short programme. A soft click and then a hiss of water means the valve is opening. A click with no water means the valve is opening electrically but not passing water. Silence means the valve is not being told to open.
- Stop there and call an engineer if the valve is at fault.The solenoid inlet valve, the pressure switch and the control board are all internal. Replacing an inlet valve means removing panels and working next to mains wiring inside a wet appliance, which is engineer work on a plumbed-in machine.
Common mistakes
- Cutting or shortening an AquaStop hose to fit — It carries a low-voltage cable to a solenoid in the head. Cutting it destroys the safety function and creates a wet electrical joint behind the machine.
- Losing the gauze filter and running without it — It protects the inlet valve seat from grit. Without it the valve fails and it stops sealing, which is how a machine that would not fill becomes a machine that will not stop filling.
If it doesn't work
Machine fills very slowly and the cycle takes far longer than usual
Cause: Partially blocked gauze filter, or a partly closed isolating valve — Fix: Clean the gauze and open the valve fully. Slow fill extends the cycle rather than erroring, which is why it goes unnoticed for months.
Fill error only in cold weather
Cause: A frozen or partially frozen supply pipe, usually in an unheated run — Fix: Warm the pipe gently with a hot cloth or a hairdryer on low. Then lag it before next winter — a frozen pipe that splits is a far bigger problem.
No water and no noise at all when the programme starts
Cause: No power, door not latched, or the control board — Fix: Check the socket and the door catch first. A door that is not fully latched stops everything on almost every machine.
Questions people ask
Can I connect it to the hot supply so it fills faster?
No. Almost every modern dishwasher is cold fill only and heats its own water precisely so it can control the temperature profile of each phase. A hot feed can damage the machine and generally voids the warranty.
The machine says it has filled but there is barely any water in the bottom.
That is normal. A dishwasher only holds a few litres at a time and recirculates them; you should see water in the sump rather than covering the floor of the tub.