Cistern and potential issues with water drainage

The pump only switches on at the upper switching point and off again at the lower one. When water comes, it rises to the upper point, is pumped out until the lower switching point, and the pump then switches off by itself.

Yes, okay. Well, the problem here is rather human in nature. I asked, an "automatic system" is not desired here, but "manually," and then you just have to keep an eye on the weather forecast to possibly "run it empty" – because ideally, the cistern is always as full as possible in case the next heat summer is imminent. I slowly believe that this is more a kind of "occupational therapy" and not really a problem.

mhh, it seems to me that the said client needs more of a fear therapy than another technical solution.

That is meant kindly and seriously.

mhh, it seems the said builder needs more of a fear therapy than another technical solution. That is meant kindly and seriously.

Don't worry, that's how I understood it and I agree with you here as well. Apparently, it is not "broken" but exactly as intended. He wants to decide for himself when to empty the cistern, or how much, and all the - in my eyes unnecessary - fuss around it is apparently a kind of "pastime" and "occupation" due to the lack of other, bigger hobbies. Well, now I know how it can be done more easily, so I will just take care of it sometime, just not right now. I thank you for your help.

Just build an overflow onto the cistern. Attach a pipe as high up as possible on the cistern, then it will always be filled to the maximum and excess water will simply run off, into the garden, to a hedge, etc.

He wants to decide for himself when he empties the cistern, or how much, and all the - in my eyes unnecessary - fuss around it is apparently a kind of "pastime" and "occupation" due to lack of other, bigger hobbies.

The behavior absolutely does not fit with the fear of erosion for me. What do you do when you are on vacation or just somewhere else for an evening and it rains heavily?

I don't quite understand the question. What good is it to tell someone who is so off track, "hey, it's all OK, the house won't fall down." Do you think they believe that?

Isn't there a way to put a drain into the channel on the property? Your remaining wastewater has to go somewhere. I would definitely prefer that to being a slave to my [Zisterne].