Siphon - which sizes are there?


The determination of the size of the siphon and the pipes of the drainage installation is always difficult. However, the number of different sizes is not so great in practice, but you must always pay attention to the selection of the right model. How to find the right and suitable siphon easily, read here.

Standardized dimensions for siphons

The easiest way to orient yourself is to measure the inside diameter of the wall connection. The result of the measurement makes it easy to deduce which of the two sizes the drainage system should have.

Basically, these sizes are referred to standardized inside diameters. There are only DN 40 and DN 50. Depending on which value fits, so you know with a simple measurement exactly what size you need the drainage system.

Only in truly antique installations can there be deviations - in this case you either have to look for suitable reducers to DN 40 or DN 50, or make a reducer yourself.

Pipe diameter

The second important size of the siphon and drainage system is the finesse. Basically, only more 1 ½ "and 1 ¼" systems are common today, with a pronounced emphasis on the 1 ½ "systems.

The Zolligkeit is so far only a small problem, because you always get adapters from one size to the other. Basically, it is easier with the right Zolligkeit.

Siphon types

In addition to the different construction of siphons, one must of course decide on application areas.

Basically, there are different systems for each:

  • bathtubs
  • bidets
  • shower trays
  • Vanities and sinks as well
  • do the washing up

For sinks, for example, a drainage system with overflow may be required, but also a tube siphon or a cup siphon (less space required) are possible. In addition, there are special variants that either meet certain design requirements, or a special space requirements are met.

For shower trays, flat siphons are usually installed, especially for floor-level showers and shower trays, which are very low. This may well be a tube siphon, but just as well an eccentric overflow. In addition, the shower tray will often require separate overflows.

There are several variations of sinks:

  • single sink
  • Double sink (mostly with drain bridge)
  • with and without overflow
  • with additional washing machine connection
  • with several options for hose fitting

Tips & Tricks

The appearance also sometimes plays a role, especially in the wash basin, where the siphon and the drain fitting are usually visible. However, such designer pieces can be significantly more expensive than a conventional waste set made of simple plastic.


Video Board: Siphon sizes and flow rates