Calculate infiltration, what amount of rainfall is possible?

We have a cistern between the roof area and the soakaway system...

Report it? Read by the municipality... So, for us, the municipality installs a separate water meter (sealed) on the cistern line (this happens automatically, so you don't need to worry about it) and when they come to read the water meter, this meter is also read...

If you keep it secret (which can only be done afterward even though you have to report it, since you have to register rainwater use for household purposes for the toilet and washing machine in the building permit) it causes trouble... Unfortunately, for us, you pay a sewage fee on the water withdrawn because you discharge it as wastewater through the toilet and washing machine into the sewage system to the treatment plant

Unfortunately, with us, you pay a sewage fee on the water you withdraw because you discharge it as wastewater via the toilet and washing machine into the wastewater sewer to the treatment plant

Why actually "unfortunately"?

This is a completely normal procedure – you simply pay the usual sewage fee for the amount of water you discharge into the treatment plant.

If this were not the case, everyone else would partially pay for your wastewater, which really wouldn't be right, would it?

hm, and if I now use a submersible pump to spray the lawn from the cistern, would that be deducted again? I hardly think so...

And would it be the same with a private well?

Why actually "unfortunately"?

That is a perfectly normal procedure – for the amount of water you discharge into the sewage treatment plant, you simply pay the usual wastewater fee.

If this were not the case, everyone else would partly pay for your wastewater as well, which really wouldn’t be right, would it?

No, that is not the case everywhere, even if it sounds logical, in some regions it is actually subsidized to make it more appealing to acquire such a system (because the savings otherwise are hardly profitable), in some municipalities the rainwater discharged into the sewer is only partially or not charged at all (according to statements by the companies Graf and Hacon that sell cisterns, I only know of one region near Wetzlar where it is like that) for example with a free allowance of a cubic meter or half the costs. Regarding garden water, you also have that with the drinking water you use in the garden… one municipality finds it sufficient for offsetting to install a water meter on the outdoor faucet, other municipalities like ours do not accept that and require an additional water meter to be installed in the line to the outdoor faucet.

By the way, the municipality wanted to install the rainwater meter behind the pump, i.e. between the pump and the withdrawal point (toilet/washing machine/faucet), but then when the cistern is empty, drinking water would have been counted twice since, when the cistern is empty, the pump draws drinking water from its own tank… So at first, we had to convince the guys by phone, then by email, and finally on site that the rainwater meter has to be installed in the suction line between the pump and the cistern.

Since an additional water meter in the line to the outdoor faucet involves even more money (it must again be a calibrated one installed by the municipality), for example, we have a submersible pump in the tank for watering the lawn, etc., so the outdoor faucet is not in use.