IBC tank instead of standpipe for construction water - possible or not?

we had water from the nice neighbor during the construction phase, an accessible garden faucet with municipal water and Gardena connection. That was sufficient for all trades and cost us only a symbolic consumption fee. Just for info for future builders

Exactly. Since you already mentioned the neighbor with her car. Buy a €20 meter at the hardware store and get the water from the neighbor.

Just as information for future builders: Such things must be approved in writing by the supplier. If I recommend someone to go through a red light because nobody is coming at the moment... I also have to tell them that they can get into trouble because of it.

What exactly does he have to approve?

Just as information for future builders:
Something like this must be approved in writing by the supplier.

If I recommend someone to run a red light because no one is coming... I also have to tell them that they can get into trouble because of it.

Exactly. And don't forget that the "contribution" to the neighbors of course also has to be taxed.

Also, it must be a water hose with drinking water approval, because if water from it is used in the construction coffee machine, then the water is considered a foodstuff...

You really shouldn't be surprised that everything is getting more expensive these days. We obviously make it harder for ourselves than it actually is.

During the construction phase, we had water from the nice neighbor, an accessible garden faucet with city water and Gardena connection.

Good and proper way.

And don't forget that the "contribution" to the neighbors of course has to be declared for tax purposes.

According to which type of income should this be? Max § 22 No. 3 with exemption limit of 256 euros. However, we are talking about surplus here. The neighbor will probably not make any.

Furthermore, it must be a water hose with drinking water approval, because if water from it is used in the construction coffee machine, the water is considered a foodstuff...

For the 3 liters per day you better leave still water from the discount store there.