The Arbia is a torrent in Tuscany, central Italy, an affluence of the Ombrone river. Its source is located in the comune of Castellina in Chianti, at 620 m of altitude. it flows into the Ombrone near Buonconvento.
The rivers is mentioned by Dante in his Divine Comedy, its waters getting "colored of red" (Inferno, Canto X, verse 86) in the wake of the Battle of Montaperti between Florence and Siena. Localities taking their names from Arbria include the comune of Monteroni d'Arbia and the frazioni of Isola d'Arbia, Taverne d'Arbia (both in the comune of Siena) and Arbia (comune of Asciano).