The water in Italy is excellent. Despite many fountains where you can refill a water jug--like this one in the picture-- nearly everyone buys bottled water, and tap water is never served at a restaurant unless you specifically ask. The conversation usually goes like this: Water, please. Still or Fizzy (in Italian)? So I was happy with whatever came.
Or, I was thinking the disdain for tap water was because of the pigeons. I heard comments that the pigeon population was drastically reduced as a result of putting the pigeons on birth control. I never figured out what the delivery system is...maybe the water--but that is purely speculation.