Rainwater must be obligatorily infiltrated

Hello dear community,

we are currently working on the construction of our single-family house. The building application has been submitted and promptly the first letter from the building authority arrived stating:

Rainwater must basically be infiltrated or discharged into a nearby open water body, as far as this is possible without disproportionate effort (§ 48 b Abs. 3 WG-BW).

After a phone consultation with the building authority, it was said that no rainwater is allowed to be discharged into the sewer, water protection zone III. The proposal is (if you can call it that, because actually it was said "there is no way around it") a cistern. In addition, permeable paving for the driveway was mentioned, whatever that may be for. By the way, there is no water body nearby.

We always thought about a cistern for watering the garden, but crossed it out because of the costs. Now we are forced to do it even though the budget does not allow it, hence the question to you.

According to Google, there are countless types of cisterns, can you tell me which one fulfills our purpose and where one should not save money in this regard?

Best regards

Just build a rigole, maybe costs 500€ and done

Why no soak pit? That's how we had to do it. Although I now prefer a cistern, especially with the water prices.

Also permeable paving was mentioned for the driveway, whatever that may be.

That is simply paving where the water does not run off on the surface but seeps under the paving. Either through pores in the paving or wider joints (and coarser joint material)

By the way, there is no body of water nearby.

That can be arranged. Dig a bigger hole in the garden and channel water into it. Without a liner of course. If it should not seep away too fast (pond look) you can compact the bottom of the hole with a vibrating plate.

According to Google, there are countless types of cisterns, can you tell me which one suits our purpose and where not to save money in the wrong place here?

Kind regards

It depends on the soil, what kind of soil do you have?
For sandy soil, even 15m of drainage pipe with seepage fleece is enough, which then doesn't even cost 100€ in materials + another 100 for a mini excavator for an hour.

Otherwise, just 2 seepage rings, chisel a hole for the KG pipe, put a lid on and you're done.

Wow, I didn't expect so many answers in such a short time!
In order :-).

just build a soakaway, maybe costs 500€ and done

When I google soakaway it looks like a box you bury and then let the water flow in with pipes. Currently we have drawn normal downpipes that then end in an inspection chamber.
How would it be with a soakaway? Instead of leading the way into the inspection chamber, just direct it to the soakaway?
How does that even work? Can you see it from above?

Why not a cesspit? That's how we had to do it. Although now I prefer a cistern especially with the water prices

Is that the same as a soakaway?
The water prices really make you think more and more about the additional costs of a cistern. As I said, we actually left it out, but somehow it increasingly looks like it makes more sense than, for example, a carport :-/.

That is simply paving where the water doesn't run off on the surface but seeps under the paving. Either through pores in the paving or wider joints (and coarser joint material)

Can you let the water from the downpipe run out directly open with that?

That's possible too. Dig a bigger hole in the garden and lead the water there. Without foil of course. If it shouldn't seep away too quickly (pond look) you can compact the bottom of the hole with a vibrating plate

Is it really that easy? How do you get the water from the roof into it then? If it seeps slower than it can flow away, wouldn't it back up the downpipe again?

depends on the soil, what soil do you have?
With sandy soil even 15m of drainage pipe with filter fabric is enough, that costs not even 100€ material + 100 more for a mini excavator for an hour.
Otherwise simply 2 soakaway rings, chisel a hole for a sewer pipe, put the cover on and done

We don't know yet what kind of soil it is (we were always told you only do a soil report once the building application is approved). The neighbors say rather clayey soil. The plot was an orchard meadow on which nothing was ever built, so a green meadow ever since.
What are “soakaway rings“? And what kind of pipe to chisel in? Sorry.