Puzzling leak from toilet!

[emeny]

Hello, just wondered if anyone has any ideas....got a persistent drip of water coming down a light fitting on the ceiling below the upstairs toilet which was put in a couple of weeks ago. There is no water on the bathroom floor, no obvious leak from waste pipe connection. We removed the toilet last night and the leak stopped completely so assumed it was coming from the cistern down the screws and we hadn't noticed it dripping. Put the toilet back in and the dripping has restarted....the toilet has not been flushed and the water level in cistern has not gone down. The valve on the water-in pipe is off. The pressure on the boiler is stable so doesn't seem to be a separate leak in the heating system. (and as I said, stopped when we removed toilet) It is a bit perplexing! Just thought I'd ask on here if anyone has any ideas before we start pulling up the floor/cutting ceiling!! Thanks!

 

[Best]

Could be a crack or hole in the bottom of the pan.

 

[emeny]

Thanks, we took the toilet outside and filled it with water and no sign of a crack....the water is now dripping from a crack along the ceiling so seems to be getting worse....

 

[Stigster]

If the water level in the pan/cistern really is not going down with the toilet inlet isolated, it can really only be from a joint in the cold pipe that feeds the toilet. The fact that it stops the leak with the toilet out and restarts when installed is a bit puzzling but there may be some strain on the pipework when the toilet is in place causing a water escape and it stops leaking when strain is removed after disconnecting the toilet.

Is it soldered copper pipework or do you have plastic pushfit joints hidden anywhere in the wall or under the floor? I'd not expect a soldered joint to behave this way under stress but a pushfit fitting might do that.

By turning the mains off or isolating the cold feed from the tank in the loft if you have one may prove whether the cold feed to the toilet is leaking before the valve or not.

 

[Aire]

Is the toilet a fully back to the wall type which hides all pipe connections?

 

[WC1]

Leaks often work their way laterally from the source to the drip. Further, wider investigation required.

 

[Coby kenny AGUILAR]

When the isolation valve is on check the slotted screw impression these let by or jet water everywhere when they show signs of age

If there's a flexi / silver braided hose check for tears along it, you can do this by putting a 15mm male cap and turning the isolation valve on to test properly,

If you don't have a flexi you will have a fibre washer, check for splits,

Check the fill valve on the Cistern, if this has a plastic thread it's probably cross threaded if it's brass it should be okay

 

[emeny]

Thank you. The water level's definitely not going down so must be the water supply but couldn't think why it stopped when toilet was removed! It is copper pipe going in with a valve that doesn't seem to be leaking so must be something under the floor....I don't have a tank, so can turn water off and see what happens...

 

[Stigster]

Yes, turn the supply off, monitor for a bit and please come back to tell us what you find. You'll be able to narrow it down.

 

[emeny]

Hello again, we have cut some flooring up and found the leak! It's on a compression fitting just under floorboards....not sure why it stopped when we removed toilet yesterday....now to try and fix it....