I have been attempting to install a new siphon flush but it kept leaking. In attempting to fix the leak, I have wrung the first one but have got a fresh one to try again.

enter image description here

The only thing I can think of is that either the silicon sealant is incorrect or the rubber washer is the wrong way around.

The sealant is tec7 (https://tec7.ie/product/tec7-sealant/) which should be ok which leaves the rubber washer.

It has a serrated edge and a flat edge.

serrated edge of washer


Does anyone know which face of the washer should interface with the actual toilet cistern?


  • I haven't seen a toilet like this, but that washer reminds me of these flapper repair kits in the US. The "flapper" is what allows water into the tank when the toilet is flushed. In this kit, the ridges would go up to seal against the rubber flapper and the smooth surface would be sealed to the opening in the "cistern" with provided sealant.
    – JPhi1618
    Feb 27 '19 at 20:38
  • 1
    @JPhi1618, the washer should be the other way around .... the ridges make the face of the washer more flexible .... extra flexibility is needed because the bottom of the tank could be uneven ..... the smooth side of the washer presses against the smooth plastic of the "lifter"
    – jsotola
    Feb 27 '19 at 22:12
  • @seanj, why don't you refer to the installation instructions? ..... also, what information is the top picture supposed to show? ....... i think that you have a leak because of all that crud stuck to the washer
    – jsotola
    Feb 27 '19 at 22:13
  • @jsotola that's tec7 sealant, the first time I put it on I didn't leave it on for 24 hours. There are no instructions with the siphon flush and the top picture is a picture of the new siphon flush bought from a plumber supplier with no part number, manufacturer or instructions.
    – SeanJ
    Feb 27 '19 at 23:21

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