Unable to answer "Is drinking water available here? If so, what is its source?" – Drinking Water – https://osm.org/node/12926027290 via StreetComplete 62.0:

Es ist Wasserspiel (im Sommer) aber kein Trinkwasser

Attached photo(s):
https://streetcomplete.app/p/319480.jpg
https://streetcomplete.app/p/319481.jpg