What is a cistern actually?


A cistern is a generally underground water reservoir and probably the oldest way people used water. The tasks and functions of a cistern range from the balance of supply bottlenecks to the guaranteed uniform supply to the protection against floods and backwater from rainwater.

Functions and properties

The best known and most obvious feature of a rainwater cistern is the collection, storage and removal of water. In the history of humanity, however, several subspecies of cisterns have developed that go beyond the capacity of a pure reservoir.

The typical tasks of the different cistern types include:

  • The permanent provision of rainwater
  • The even and controlled distribution of water
  • The balancing and channeling of high rainfall through heavy rain
  • The storage and dosing of extracted well water

Installation method, economy and ecology

In most cases, cisterns in the form of tank containers are buried in the ground or buried. The usual hollow dimensions range between the capacity of 2000 and 20,000 liters.

In the private sector, garden cisterns are preferred to ensure plant irrigation. Also monetary aspects such as a reduced consumption of public drinking water and a saving by split sewage charges play an important role. Ecological aspects, the conservation of resources, are increasingly coming to the fore as another important argument.

Concrete and plastic

Usually, concrete tanks or plastic cisterns are selected, which are available as prefabricated components. Depending on the intended use, the cisterns have the appropriate connection options, in order to enable use beyond plant irrigation.

Planning factors and alternatives

When considering whether a cistern is the right choice, several factors must be considered. In addition to the intended use, consideration must be given to the regional regulations for approval and climatic conditions. Alternatively, depending on the criteria, a groundwater well may be the more appropriate choice.

In particular, in an intended extensive recovery of water for example, for toilet flushing or washing machines or the connection of the cistern to a domestic waterwork should be planned exactly what what type of cistern can afford.

retention cisterns

So-called retention tanks have a different task than forming a water reservoir. They serve to compensate for very heavy precipitation, which they absorb and metered forward. As a buffer, the large quantities of water absorb, store and release them with a time delay when precipitation has receded like heavy rain.

In order to increase this effect and to ensure a faster removal of the "collected" rainwater, retention tanks are often combined with a drainage system.

Tips & Tricks

You can combine the function of a retention tank with the use of water. The regulatory requirements for this are relatively extensive and often narrow.


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