01 Sept 2026
There is a puddle at the foot of your toilet that keeps returning after you mop it, and nothing above it looks wet. Water at the base of a pan is one of three very different leaks, and the repair is usually straightforward once you know which one you have. You can narrow it down yourself in an hour, without tools.
First, make sure it is a leak
Dry the floor around the pan, go over it again with kitchen paper so you will see the moment it returns, and lay strips of dry tissue hard against the base at the front, the sides and the back. Then leave it alone. Do not use the toilet, do not shower, and come back in an hour.
Two things imitate a base leak. A cistern full of cold water sweats on a humid day, and that condensation pools exactly where a real leak would. And water from a shower or a weeping basin waste runs along a sloping floor to the lowest point, which is very often the toilet. If one side of the tissue is soaked and the rest is dry, follow the water uphill.
The test that tells you which leak it is
Once the floor is dry, the timing tells you nearly everything.
- Wet only after a flush. The seal between the pan and the waste pipe, or the pan connector itself, has failed. This is wastewater, so it usually arrives with a smell.
- Wet constantly, clean water, no flushing needed. The leak is on the supply side: the inlet hose, the inlet valve, or on a close-coupled unit the bolts and gasket between cistern and pan.
- Wet only when someone showers or uses the basin. It is not the toilet.
To narrow down the second one, put a few drops of food colouring into the cistern and leave it without flushing. Coloured water at the base is escaping from the cistern or the joint beneath it. Water that stays clear never reached the cistern, which puts the inlet hose and the mains valve at the top of the list.
Does the pan rock?
Sit on it and shift your weight, gently. A pan that moves at all works the waste seal loose every time it is used, so renewing that seal without fixing why it moves buys a few months and no more. Movement means the fixings have loosened or the bedding under the pan has broken up, and both are dealt with when the pan is lifted.
A hairline crack in the ceramic is the other thing to look for, usually low down and hidden in the shape of the pedestal. It weeps steadily, it cannot be patched, and the pan needs replacing.
Why silicone around the base is not the fix
This is the usual first response and it makes things worse more often than it helps. Sealing the joint between pan and floor does not stop water leaving the waste connection. It stops that water from appearing, which is a different thing entirely, and the leak carries on underneath, soaking into the screed.
That matters more than it sounds. Water working under a pan travels through the floor build-up and downwards, and a slow toilet leak is a genuine cause of the stain that turns up in the ceiling below. If a neighbour has mentioned a damp patch, our post on a ceiling leak from the unit above covers it from the other side.
When a pan is refitted properly, the seal at the waste connection is what holds the water back. Sealant around the base is cosmetic, and leaving a small gap at the rear is worth asking for, because it lets a future leak show on your own floor rather than announce itself downstairs.
What to do while you wait
If the water arrives after flushes it is wastewater, so keep the area dry and use another bathroom if you have one. If it arrives constantly, close the small isolation valve beside the cistern and flush once to empty it.
A cistern that never stops refilling is a different fault, and our post on a toilet that keeps running deals with that one.
What the repair involves
Reaching the waste seal means draining the cistern, lifting the pan clear, cleaning both faces, fitting a new connector or seal, re-bedding the pan level and testing it over several flushes. It is not a long job in an ordinary bathroom, but a pan put back onto a broken bed will leak again.
Our toilet repair work covers all of that, and the pricing page shows where common toilet jobs start. An on-site survey starts from $30 and covers the trip and the diagnosis.
When to call a plumber
Call when the water arrives after flushes, when the pan rocks, or when you have dried the floor, watched it and still cannot say where the water comes from. Call sooner if there is a damp patch on the ceiling below or a smell that will not clear, because both mean water has been going somewhere for a while. A weeping cistern connection can wait a few days, as long as you have closed the isolation valve.