Dimension Cistern - Building Plan Tips

Whereby the OP has an obligation that the water must either infiltrate or be used otherwise.
Therefore, at least part of the costs would have to be spent to accomplish at least one infiltration. Of course, one could also consider whether adding sum X on top would be sensible.

Btw. - I am surprised by the passage stating that no connection to the sewer system is allowed (not even an overflow).
They always referred to the last, very dry year. BUT:
If I look at this year, where in RLP a precipitation amount of 145 l/m² was measured in June, even a 10 m³ cistern would not be sufficient.
11 * 10 base area = > 110 m² (actually even larger because of the slope)
110 m² x 145 l = nearly 16,000 l

Ergo - "The tub is full, uh uh uh, the tub is full ..."

No major withdrawals took place in June anyway - what for.
Unfortunately, the cistern was already well filled earlier this year as well. So - where to put all the rest. Infiltration could have also become difficult in June this year. Because the soil was already saturated.

It is correct that the OP has an obligation, hence my restriction to those who do not have to build a cistern.

11 * 10 floor space = > 110 m² (actually even larger due to the slope)
110 m² x 145 l = just under 16,000 l

In my opinion, the slope does not have a significant impact, only the roof overhang.
In addition, there is the 36 m² double garage. Total therefore already 20 m³.

I was also surprised by the OP’s statement to reduce the cistern and instead drill a well, because then the problem with the overflow would be even more extreme. Furthermore, this would involve an additional investment, which presumably would not pay off either and is not mandatory. If he is not allowed to discharge anything, then he would probably have to build a soakaway behind it for infiltration or contaminate the water in order to be allowed to discharge it.

In addition, there is the 36m² double garage. So the total is already 20m³.

I was also surprised by the OP's statement to reduce the cistern size and instead drill a well, because then the problem with the overflow would be even more extreme. Moreover, this would involve an additional investment here, which presumably would not pay off either and is not mandatory. If he is not allowed to discharge anything at all, then he would probably have to build a soakaway system behind it for infiltration or contaminate the water to be allowed to discharge it.

I conveniently overlooked the garage.

I assume the idea of the well came about due to the discussion "Is a cistern worthwhile or not" and "how much water is needed for irrigation." Therefore, he wanted to reduce the cistern as much as possible and rather drill. However, a not insignificant part of the mentioned costs, in my opinion, is for the earthworks. When we were considering whether to have a 5 m³ or 10 m³ concrete cistern, by the way, our general contractor said that the additional costs would be between 500 - 800 euros (max. 1,000).
Whereas then the OP could possibly omit the cistern completely and only install an infiltration system that fully absorbs the water (as far as his soil allows). The money saved could then actually be invested in the drilling.

Hello

I have a 10 m3 concrete cistern. Although it was 10 years ago, the thing cost about 2,000 Deutsche Marks including transport. Then another 1,000 for the piping and the filter. I am very satisfied with it. Always cool clear water. The overflow goes into the sewer. In the basement, I have a domestic water system and in the garden three tap points. Now I am burying a fiberglass tank with 4m3 under the greenhouse. I got it on Ebay for 40 euros. Rented a trailer (25 euros) and picked it up myself. You can never have enough water.

Steven

Now I'm burying a fiberglass tank with 4m3 under the greenhouse. I got it on Ebay for 40 euros. Rented a trailer (25 euros) and picked it up myself.

If you bury the tank under the greenhouse – will you also install an electric pump here or connect a hand pump?
Is the fiberglass tank meant to collect the roof drainage from the greenhouse or how is the filling done?

Hello,
An ordinary barrel pump will be installed there.
I turn on the tap and let it run from the concrete cistern until the barrel is full. It's actually more of a reserve,

Steven