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Discuss Toilet intermittently blocking?! in the Plumbing Forum area at

  1. joey2468

    joey2468 New Member

    Hi all,
    Posting in behalf of my parents who have just moved into a new house last week, always had a slowly draining toilet but today seemed to get blocked and water slowly draining away. There seems to be an intermittent siphon effect where the water drains lower than the waste pipe is (if that makes sense) and it bubbles and gurgles at times. Cistern fine.
    Checking outside the waste drains appear clear.
    All symptoms are intermittent and sometimes it will drain completely fine which is the confusing part to us.
    Tried plunger and lots of boiling water and then some unblocker all which seemed to help initially.
    Anyone got any thoughts?? Thanks in advance.
  2. Chuck

    Chuck Active Member

    Drains have air vents to keep the pressure inside the pipe equal to the pressure outside. When one of these is missing or blocked you get symptoms like those you describe.

    Can you provide photos showing the drains?
  3. joey2468

    joey2468 New Member

    Hi Chuck,

    Have attached pictures, hopefully they are helpful.


  4. Matchless.plumb

    Matchless.plumb Trusted Plumber GSR

    That doesn't seem like the right waste pipe for the toilet cannot see and branch for the toilet of wash basin.
    Are you sure that's the main soil pipe for the waste.

    Did you check the back of the toilet if the waste is properly installed ?
  5. ShaunCorbs

    ShaunCorbs S. Mod Trusted Plumber GSR Top Contributor!!

    Yes it is toilet go straight into the ground (prob with the old style clay pipe and p trap toilet)
    • Like Like x 2
    • Agree Agree x 1
  6. Chuck

    Chuck Active Member

    I suspect a blockage either of the black vertical soil vent pipe (SVP) or, more likely between the SVP and the point the toilet joins the drain.

    This could have happened during a previous attempt to rod the drain when a blockage initially downstream from the toilet branch may have got pushed upstream. The toilet would have sort of worked in the way you described but the root cause is still down there.
    • Agree Agree x 1
  7. jtsplumbing

    jtsplumbing Plumber GSR

    Have you no inspection chamber (Manhole) you can check ? Proberly under the shed, other possible cause is tree roots , reflection in window showing lots of trees
  8. Chuck

    Chuck Active Member

    Good point.

    Note for the OP: If the cause does turn out to be tree roots you should get a drains specialist to survey and advise. Roots are a sign that the drain is leaking or broken and needs repairing, either by relining or replacing.

    Let's hope the block is just an old nappy someone tried to flush!
  9. Matchless.plumb

    Matchless.plumb Trusted Plumber GSR

    Never seen that before :) still learning English ways hahha
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