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Discuss Puzzling leak from toilet! in the Plumbing Forum area at

  1. emeny

    emeny New Member

    Hello, just wondered if anyone has any 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!
  2. Best

    Best Trusted Plumber

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

    emeny New Member

    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..
  4. Stigster

    Stigster Plumber

    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.
    • Agree Agree x 1
  5. Craig Watson

    Craig Watson Plumber GSR Top Contributor!!

    Is the toilet a fully back to the wall type which hides all pipe connections?
  6. WC1

    WC1 Active Member

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

    Coby kenny AGUILAR Member

    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
  8. emeny

    emeny New Member

    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...
  9. Stigster

    Stigster Plumber

    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.
  10. emeny

    emeny New Member

    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 to try and fix it..
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  11. Stigster

    Stigster Plumber

    As mentioned above, I expect that when the toilet was connected it put some strain on the pipework and opened a leak on a "just about sealed" compression fitting. With the toilet disconnected the pipework was able to relax a bit, just enough to stop the leak. It's amazing the weird stuff fittings and water can do at times.

    I've seen fittings that were fluxed but missed at the point of soldering not leak for years, held together by the dried on flux. I've touch the pipe and it's fallen apart and started leaking.

    I hope you've managed to sort your leak out and all is back to normal by now or at least on its way.
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  12. CBW1982

    CBW1982 GSR Top Contributor!!

    I’ve had that on a gas fitting once :eek::eek::eek:, it wasn’t mine before anyone says :p
  13. MikeJhn

    MikeJhn Active Member

    Why does that happen, I'v found three in the last two years in house's I'v bought for renovation, quite perplexing, Oh yes this is in France, so think its not just British plumbers? or is it? ;)
  14. Best

    Best Trusted Plumber

    Typical reason is a lot of plumbers must be fluxing and pushing on the pipes more than one solder fitting before heating and soldering them all.
    Therefore very easy to forget about an unsoldered connector a few few away from a soldered tee, etc.
    I generally solder each fitting before pushing another together
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  15. MikeJhn

    MikeJhn Active Member

    I never flux a joint until I am ready to solder, so don't think I have ever missed one, famous last words come to mind.
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