The Elvo is a 53-kilometre (33 mi) torrent in the Piedmont region of north-west Italy and is the principal tributary of the Cervo. It runs through the communes of Sordevolo, Occhieppo Superiore, Occhieppo Inferiore, Cerrione and Salussola in the Province of Biella, and of Carisio and Casanova Elvo in the Province of Vercelli.