Unable to answer "Is the water potable here?" – outside: Fővárosi Vízművek Zrt. (Water Tap) – https://osm.org/node/6600848935 via StreetComplete 57.1:

Itt nincs utcai kút.

Attached photo(s):
https://westnordost.de/p/204529.jpg
https://westnordost.de/p/204530.jpg