Rainwater cistern: Useful? Necessary? Costs?

Do you have a submersible pump in the cistern?

Yes. The pump leads directly to the garden faucet. The cistern is positioned directly in the driveway, where the downspouts in front of and behind the house are connected directly to the cistern. The overflow of the cistern (still above the backwater level - we live slightly above the street) leads to the combined sewer.

Is the soil survey already available?

Our building authority also considered a cistern desirable. We already had to lay two pipes for the future sewage system, which currently lead into the combined system but will separate gray water and rainwater in the future.

We could not install a cistern. The reason: tense groundwater. So the authority's wishful thinking remained. We were happy about the cost savings.

A cistern only pays off if you have a large garden. Using Ethernet LAN cards, the good water can be distributed quite easily in the garden and on the balcony boxes (via hoses). Depending on the weather forecast, the garden irrigation system can then be controlled from abroad without any problems. However, if you only need 20 m3 of tap water annually in your home garden, you don't need a cistern. Two 210-liter green bins are sufficient and that's fine. ps. abroad, you can easily operate the toilet flush with it (separate water circuits to the flush tanks). Often green moss in the WC.... but still okay in terms of color.

We are allowed to direct our rainwater directly into a gutter that flows into a small stream a few hundred meters away. This way, we save the fee for stormwater.

The effort to install a cistern for garden irrigation has not paid off over the next few years according to my calculations. Therefore, I have abandoned that and prefer to take the water directly from the regular tap without a pump.

Edit: If the garden should become larger, there might also be a water barrel at the downpipe behind the garage.

How do I get rid of my rainwater when, according to the development plan, every property owner has to infiltrate the water themselves? A retention basin is not a solution. The problem here: the construction company always initially includes a retention basin in the building application, but a later change is problematic here because the responsible person at the office is hopelessly overloaded (small village, large new development area, and who wants to work temporarily somewhere for peanuts as a specialist...). I basically need the rainwater infiltration principle this weekend so that I can still include it in the application next week. I would imagine that somewhere behind the house in the garden a tank or something similar is buried, into which the water from the house roof is collected and infiltrated. Garden irrigation or something similar is not necessary. Neighbors are installing a shaft, but isn’t that even more expensive?!

how do I get rid of my rainwater if, according to the development plan, every property owner has to infiltrate it themselves?

Again... I just reviewed my old documents: it's called a rainwater infiltration shaft, installed by the earthworker at the same time as the supply shaft (sewage). The former is then connected to the rain downpipes, collects the rainwater and lets it infiltrate little by little, as required by the building authority. For us, 20 linear meters of pipes to the downpipes were included. Including digging, pressure test for the supply shaft, and VAT: €3300. No pumps, fiddling or rainwater collection for the garden. What must be, must be... for us it only became an issue in the last quarter of the construction phase... at that point we had no desire for technical fuss.

Regards Yvonne