That is unreasonable to demand from the municipality's side, isn't it?
Incomprehensible, uneconomical maybe or just simply exaggerated. Anyone who perceives this as a "demand" has led a very sheltered life. Calculate the ROI yourself and then decide, it's not difficult. It's not worth getting upset about.
Can someone explain to me in more detail why one would want this? You would only need it if I understood correctly when watering the garden with the house water line so that you don't pay sewage charges on the withdrawal, right? If I water with cistern water, I can skip this, right?