I've noticed some cisterns have siphon units that are not secured at the top. Every time the toilet is flushed, the top of the siphon moves or tilts to one side. For example, in the following youtube video.


Is this part of normal operation, or is there is any merit to securing the siphon in these cases?


That's going to depend on the type of valve and the material it's made of. In your video, the valve moves because of the force to lift the flapper. That's normal. You just have to make sure the valve is tightened to the tank correctly so water doesn't leak out each time you flush and the valve moves. There i no reason to try and design a method to secure it, just install it correctly.

  • This is specific to the lightweight ones made of plastic. If this is part of normal operation, I'm surprised the constant movement doesn't make it more likely to leak at the base. – Brybeck Dec 25 '19 at 14:19
  • I think the valve or parts of it will need replacing long before the washer gives out. – JACK Dec 25 '19 at 14:24
  • Keep in mind that the video is set up to advertise the valve and there's probably some "play" in the plastic tank that contributes to the movement. in a real situation, the movement would be less. – JACK Dec 25 '19 at 20:45

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