I can hear water running, but every tap is off
A hiss in the wall, a trickle under the floor, or a toilet that seems to fill on its own in the middle of the night: hearing water when nothing is turned on is unsettling, and it usually means water is going somewhere it shouldn't. Sometimes it's a simple fix, like a toilet valve. Sometimes it's a leak inside a wall or under the slab. Here's how to work out which, and what to do next.
The most common causes
A toilet that keeps refilling
A worn inlet valve or flush seal lets water trickle into the bowl, so the cistern tops itself up every so often. You'll often hear it at night when the house is quiet. See our running toilets guide.
Hot water system
A relief valve dripping or a heater refilling can sound like running water. Check the drain pipe from the relief valve outside. See relief valve dripping.
Leak inside a wall or floor
A steady hiss in one spot, often near a bathroom or kitchen, can be a pinhole leak in a pipe hidden in the wall or under the slab.
Underground water service
A leak in the pipe between the meter and the house may be heard at the meter or where the pipe enters the house.
Rainwater pump or tank
A pump that cycles on and off, or a changeover device letting mains water through, can sound like running water. See our rainwater tank page.
Neighbours' plumbing
In semis, terraces and units, the water you hear may be in a shared wall. The meter test below tells you if it's yours.
Check it yourself in ten minutes
- Toilets: put a few drops of food colouring in each cistern. If colour appears in the bowl within 15 minutes without flushing, that toilet is leaking.
- Meter test: turn off every tap and appliance, note the water meter reading including the red numbers, and check again after an hour. Movement means a leak somewhere.
- Hot water: look at the relief valve drain outside. Constant running water is worth a call.
- Listen: walk the house at night and note where the sound is loudest.
How we track it down
We start with the fixtures, then pressure test the water lines to confirm whether there's a hidden leak. If there is, we use acoustic listening equipment and thermal imaging to pinpoint it before we open anything up, so any hole in a wall or floor is small and in the right place. You get clear options and a fixed price before any work starts.
Hidden leaks in southern Eastern Suburbs homes
Older homes in Matraville, Maroubra and Kingsford often still have copper or galvanised pipes that develop pinhole leaks after decades of high mains pressure. In units and semis in Maroubra and Kensington, sound travels through shared walls, so it's worth doing the meter test before assuming the leak is yours.
Why locals call us
- Local to Matraville and the southern Eastern Suburbs
- Free on-site quotes, with a fixed price before any work starts
- Lifetime labour warranty on our workmanship
- 100+ five-star Google reviews
- Licensed plumbers and gasfitters (Lic. 398171C)
Common questions
Why can I hear water running when nothing is on?
The most common causes are a toilet that keeps refilling, a hot water relief valve, or a leaking pipe in a wall, floor or yard. A meter test tells you whether water is actually escaping.
Why does my toilet fill up by itself at night?
Water is slowly leaking from the cistern into the bowl past a worn seal, so the inlet valve tops it up every so often. A new valve or seal usually fixes it.
Can you find a leak without knocking out walls?
Yes. We use pressure testing, listening equipment and thermal imaging to pinpoint the leak first, so any opening is small.
Is a hissing sound in the wall serious?
It can be. A steady hiss can be a pressurised pipe leaking inside the wall, which can cause damage and mould over time. It's worth getting checked quickly.
Related help: leak detection, hidden water leak guide, leaking toilets, wet patch in the yard and water shut-off guide. Local pages: Matraville, Maroubra, Kingsford and Kensington.