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Discuss Concealed Grohe Cistern Leak? in the Plumbing Forum area at

  1. Dee

    Dee New Member

    Hi, looking for some advice regarding my concealed Grohe cistern.

    Problem 1 - There is a small amount of water appearing around the right hand side at the base of the tiling which houses the cistern and this has been happening for a few months but hasn't worsened. (I initially thought it was condensation).

    Problem 2 - Vary occasionally, the cistern continues to fill until it overflows into the pan. This happened tonight, first time in ages but simultaneously there was some increased seepage from the tiles whilst the cistern was re-filling. I wiggled some bits inside the cistern (clearly I'm not a plumber ) and stopped the continuous filling but the steady seepage continues. Help!:confused:

    Problem 3 - A few months ago I consulted the plumber who fit the toilet in 2014 and he said it might be best to replace the whole thing with a standard toilet. Not ideal as it would mean re-tiling etc and not to mention the ridiculously expensive light up flush plate I bought would be redundant:(

    So, in short I would love to know if this is a flush valve issue, a leak from the the flush pipe, both or something else. Either way do I abandon hope of fixing and replace the whole thing or should I find a new plumber who can fix?

    Many thanks in advance for reading through to this point..

  2. Riley

    Riley S. Mod Trusted Plumber GSR Top Contributor!!

    Depending how it’s tiled you may be able to remove the pan and check for leaks. Hate concealed units for this very reason
    • Like Like x 1
    • Agree Agree x 1
  3. CBW1982

    CBW1982 GSR Top Contributor!!

    I agree with Riley, if there’s access thenyou can sort form there. The leak(s) could be both. If it reaches overflow level, if no rubber seal has been used or it’s not fitted correctly or perished then this will allow water to seep out. The flush pipe could also be leaking when flushed from various places. You’re going to need some form of access to repair.

    • Optimistic Optimistic x 1
  4. SimonG

    SimonG Trusted Plumber

    Need to pull the toilet pan out. Will be the crappy push fit seal on the bottom of the cistern. Can buy replacement seal kit. But also needs flush valve or inlet valve sorting as well.
    • Agree Agree x 1
    • Informative Informative x 1
  5. king of pipes

    king of pipes Trusted Plumber GSR

    Only option is to isolate the inlet valve flush and hold to drain the cistern and then remove the toilet pan , have a couple of old towels handy to catch any spilt water check the seal at the base of the cistern and for visable signs of leakage. Kop
  6. Dee

    Dee New Member

    Thank you.
  7. Dee

    Dee New Member

    Cheers. Push fit seal a definite prime suspect. Still considering ripping the lot out.
  8. Dee

    Dee New Member

    Thank you, I won’t be fitting a concealed cistern when I get the extension built
    • Like Like x 2
    • Disagree Disagree x 1
  9. Dee

    Dee New Member

    All tiled in but have spare pack of tiles in loft. Thanks for your help.
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