Hello, thank you for your comment ! As I am not speaking fluently italian, I prefer answering in english, sorry for that. I have been travelling by bike in the area during mid-january. In such conditions, drinking water was an important preoccupation for me. I have met a lot of unfunctional drinking water through South Italy and Sardinia so it's hard to exactly remember each place but I'll try to do my best :
* In Molfetta, the place in front of the cathedral where was placed the drinking water POI seemed to have been recently renovated as there were still some road works there. The place mostly empty and as the POI was placed in the middle of it, I am pretty sure there was nothing anymore.
* For Barletta, I don't remember the fountain you mention but I found it on Street View. But as you said, it looks more like a decorative fountain so that's why I struggled to find it. I have restaurated the POI, but, for me, it makes more sense to use `amenity=fountain, drinking_water=yes` as stated in the wiki : https://wiki.openstreetmap.org/wiki/Tag:amenity%3Dfountain. See changeset : https://www.openstreetmap.org/changeset/163906910
* For Canosa, I remember the water tap, and it wasn't working. As I mentionned it in the note I left the day I past there, the handle was broken so it was impossible to get water from it. If you do prefer, I have restaurated the POI and indicated it is not working anymore with `disused:amenity=drinking_water` as stated in the wiki : https://wiki.openstreetmap.org/wiki/Tag:amenity%3Ddrinking_water. See changeset : https://www.openstreetmap.org/changeset/163906735
Tell me if it's ok for you ?