The authors agree that Passalacqua derives from the phrase passa l’acqua, with the meaning of “one who crosses the water,” designating the ferryman or boatman who carried passengers across watercourses or between nearby banks. The surname thus originated as a label for the trade.

E. De Felice notes that, in southern Piedmont and in Liguria, the surname may also reflect the place name Passalacqua, located in the Alessandria area.

F. Miranda indicates that the surname is spread across all Italian regions, with an important nucleus in Sicily and another in central-eastern Liguria, besides a presence in Tuscany, Lombardy, Lazio, Piedmont, Abruzzo, Emilia-Romagna, Calabria and Apulia. In Sicily it appears in the areas of Messina, Trapani, Palermo, Catania, Agrigento and Enna.

V. Blunda stresses the Sicilian dialectal character of the surname and specifies that the compound pàssa l’acqua specifically designated the ferryman who crossed watercourses or joined nearby banks, and that its transformation into a surname arose from the label of the trade.