Answer from Erwin Nolde: 

We have created great concepts on behalf of the municipality, but nothing has been implemented so far. The brakes are often being applied here - they would like to have lighthouse projects, but only according to the generally recognised rules of technology, which by definition must have proven themselves for at least 30 years. There are too many people with reservations at too many levels.

We "only" need willing clients - no one could or wanted to forbid us from implementing the projects I showed in the webinar on closed-loop urban farming.

One strong opponent are the lobbyists of the water supply and sewage disposal companies, who have the best connections to politics and who, against their better judgement, constantly predict a relapse into the Middle Ages.

In Berlin, for example, rainwater charges actively discourage the use of rainwater.