Dimension Cistern - Building Plan Tips

And those who only need to infiltrate do not necessarily also need a cistern (Retention).

Hi,

Are garden fountains out of fashion by now, or are they not allowed in many municipalities?

I can only speak for the Nürnberg region here, but here in Franconia, garden fountains are usually no longer permitted.

Best regards,
Andreas

this is official... for this I get about 2500 m^3 of fresh water here. I will never need that much in my garden in my lifetime...

and that is exactly why such a cistern - made totally official like that - is never sensible. such a cistern is certainly worthwhile for someone who does all the work themselves. but if you have it done by company so and so, you can achieve nothing with it.
whether it is morally okay or not to use fresh water for irrigation is something everyone has to decide for themselves. on the other hand, several liters also flow down the toilet every day...

that's official... I get about 2500 m^3 of fresh water here. I won't need that much in my garden in my lifetime...

If you "only" have a lawn, probably not. We have several beds and a greenhouse, so it adds up. Unfortunately, I can't find reliable numbers quickly, but with roughly estimated 150 m3 of garden water per year, it takes about 15 years for the cistern to pay off. Since we are building new, that is actually at least our goal.

However, the cistern would always have to be optimally filled and nothing should seep away, because with 700 mm of rainfall per year and 200 m2 of roof area, only 140 m3 of rainwater will arrive – and not only in the summer, when we need most of the water. So if I calculate with 100 m3 of usable rainwater, we're already looking at over 20 years to break even... then it somehow becomes unprofitable.

Maybe it will only come down to rainwater barrels and fresh water out again :-/

Hello,

However, for this the cistern would always have to be optimally filled and nothing allowed to seep away, because with 700mm of rainfall per year and 200m2 of roof area, only 140m3 liters of rainwater will arrive – and not only in summer, when we need most of the water. So if I calculate with 100m3 of usable rainwater, we are already at over 20 years break-even... then it somehow becomes unprofitable.

Your calculation is still quite optimistic. Our neighbors had a cistern installed back then (I think 4 m^3) and they say they get it filled maybe 5-8 times a year. With about 100 sqm of roof area and thus about 65 m^3 of usable rain. Unfortunately, it usually rains when I don't need the cistern. And in summer we often have several weeks of dry periods here (even last summer, which apparently was very rainy in many regions).

Economically, it won't work out. Although the water price will certainly rise. But then you also have to offset the financing costs for the €4600.

It only becomes interesting if you either have to build an infiltration system anyway or if a cistern leads to no longer having to pay a fee for the stormwater.

Best regards,

Andreas

Economically, this won't work out. Although the water price will certainly rise. But then you also have to factor in the financing costs for the €4600.

The water price here has been stable since 2001, and according to Google ("Development of water prices in Germany") it roughly keeps pace with inflation. So as long as there are no really drastic climate changes and drinking water doesn't become scarce (like currently in Cape Town), I don't see any major changes here...

It’s only interesting if you either have to build an infiltration system anyway or if a cistern means you no longer have to pay a fee for rainwater.

That is exactly my issue. In 20 years, I will already be paying over €6000 in rainwater fees for my 200m2 area... you can do quite a bit with that money.