Connecting the siphon - this is how it works


If you connect a sink, the wastewater must be connected. In our detailed guide you will learn step by step how to properly connect the siphon and what you should pay special attention to.

Components of drain fittings

A pop-up waste can be subdivided into three sections - regardless of whether it's a sink or a sink.

  • the dip tube leading from the drain valve to the siphon
  • the siphon itself, which is available in different versions and
  • the sewage connection pipe leading from the siphon to the sewage connection in the wall

In some cases, the dip tube can also be omitted, the siphon is then connected directly to the drain valve. There are also extensions and special moldings to the individual pieces (except for the siphon itself).

Cut tubes to length

In any case, the siphon should sit exactly vertical and exactly in front of the waste water connection. If this is not possible for installation reasons, the lateral difference must be compensated by appropriate fittings (dip tube with offset) or by a flexible waste water hose.

Submersible pipes must always be cut to length (if they are not adjustable) so that the waste water connection from the siphon is level with the wall connection. The wall connection pipe must also be shortened so that the siphon hangs in the correct position and the immersion pipe (if present) is exactly vertical.

Pipe length inside the siphon

The length of the pipe must be chosen so that the pipe does not extend in full length into the connector of the siphon. It must be observed 10 mm "pipe play". This can easily be measured by first pushing the pipe into the fitting as far as it will go and then pulling it back by 1 cm.

Connecting the siphon - step by step

  • siphon
  • Pipe lubricant (very helpful)
  • pipe wrench

1. Cut the tubes to length

Try to connect the dip tube and the water pipe to their connections. Now determine where you need to cut the tubes to length so that the siphon is in the correct position. Cutting to length is best done with a fine-toothed metal saw. Then carefully remove the burrs and file plastic pipes on the edge to make them easier to slide into the connectors later.

2. Assemble the siphon

Place the gaskets on the pipe ends (they must always be pushed onto the pipes, not pressed into the fittings!). Apply a thin coat of lubricant to the pipe ends and insert the pipe ends into the fittings. Temporarily tighten the union nuts.

3. Finish

Then adjust the siphon until it is in the correct position. Hand-tightening is sufficient, especially for plastic drainage sets. An additional seal in the area of ​​the union nuts is not absolutely necessary and can usually be omitted. Check the secure seating of all connections and test the drainage system for leaks.

Tips & Tricks

Flexible connection hoses are basically a good thing. But you should still cut the dip tube as accurately as possible, and do not try to make inappropriate lengths with the hose. Make sure that the hose is as short as possible and that the siphon is in the correct position.


Video Board: bell siphon 1 John Introduces The