Cost of cisterns, systems for collecting/retaining precipitation

Good morning dear construction community :)

Since the building regulations of our community require a cistern, I wanted to ask you what costs I should expect? The installation or burying of this system should not be too difficult, so I can probably do it myself.

Our property has 379m² and the following building regulation:

3.9 Systems for collecting and retaining rainwater (§ 74 (3) No. 2 State Building Code)

3.9.1 For the rainwater generated, systems for collecting and retaining with delayed discharge into the separate sewer system must be installed on the properties (e.g. green roofs, retention cisterns, reuse of greywater, etc.).

3.9.2 Rainwater from commercial yard areas with typical commercial surface loading (surface type ≥ F4, cf. guidance for handling rainwater in urban areas – LUBW 2005) may only be discharged into the public rainwater sewer if it is sufficiently pre-treated. Plans for rainwater treatment must be submitted to the lower water authority to obtain the necessary permits.

3.9.3 The discharge of operational wastewater into the public rainwater sewer is not permitted.

3.9.4 Outdoor areas where water-polluting substances are handled (e.g. loading and unloading areas) must fundamentally be sealed liquid-tight according to the generally accepted rules of technology. These must be connected to the wastewater sewer or covered. Whether a permeable surface sealing is permitted can be roughly estimated using the assessment procedure of the guidance for handling rainwater in urban areas.

NOTE: Drainage systems must be constructed according to the generally accepted rules of technology and require approval by the municipality.

Hello,

so our retention cistern with a total volume of 9100 and 6500L retention cost me €2129.
We did the excavation ourselves.
The cistern is made of concrete by Mal with a lid placed on it at the factory.

Hello Waldemar, the topic of cisterns has already been discussed a few times. Often about whether it makes sense or not - which is not necessary for you due to the regulation. But during the discussions, prices for the different sizes of cisterns and also the calculation of the size were usually discussed. Just search for it in the forum and you will certainly find something suitable.

Hello Jochen,

yes, I have already read them too, but in my case it is due to the building regulations, which is why it is not just a standard cistern but a retention cistern or systems for collecting and holding back for delayed discharge into the separated water system.

My house construction company estimated about 4000€ (external company) and reported that they also had a case nearby where in the end, due to the building regulations, it was even 8500€ (2 pumps, throttling & buoyancy protection).

Yes, but no one here will be able to tell you whether the 4k case or the 8.5k case applies to you.

The building regulations only state the above, so how is one supposed to know which cistern to choose now?

As I understand it, the following cistern should be sufficient for me.

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