Backflow preventer in the drinking water installation - what does one need it for?

Exactly what non-return valves are, how they work, and why they are so important in drinking water installation in the pipes explains in detail this post.

Function of non-return valves

Backflow preventors take on the task of allowing water to flow in pipes only in one direction. If the flow direction reverses, or if a reflux pressure arises, they close automatically. If the flow direction changes again in the desired manner, the backflow preventer opens again by itself.

Construction of non-return valves

Anti-kickback devices can be constructed in very different ways. There are:

  • Bolting systems (such as a gravity brake)
  • Flap systems (such as a non-return flap)
  • Valve systems (eg ball valves)

In addition, such systems are often combined with pipe aerators to form a complete system.

Use of non-return valves

In the installation technique, non-return valves are used for various purposes. For example, a certain form of non-return valve sits just behind the water meter. He should prevent that when it comes to pressure fluctuations in the supply network, the water when running back and the water clock running backwards. If that happened, the actual amount of water removed could never be accurately determined.

Also to prevent the drainage of pipes or risers, which is undesirable in drinking water installations, non-return valves are used. Likewise, pumps should be protected from recoil waves caused by sudden backflow of water. Such kickbacks can damage a pump in the installation area. In combination with pipe aerators, non-return valves are very common.

In many fittings (such as the bathtub hose) are built-in backflow preventer so that no non-drinking water - like the water from the bath tub - would be sucked back into the drinking water installation.

In the heating area, non-return valves are also used to safely separate different heating circuits from each other. Also to prevent the unwanted heat buoyancy they are used, sometimes in special versions.

Particularly important is the use of non-return valves in relation to the fight against Legionella. In the DIN EN 1717: 2001-005 technical rules are defined, which are to prevent in particular a contamination of the drinking water by return flow.

Tips & Tricks

Basically, it should be kept in mind that any intervention in the drinking water system through a connection (such as an external connection in the garden) poses a risk to drinking water quality and should be adequately secured.

Video Board: Install Backflow Device for Safe Drinking Water