Transacqua was a comune (municipality) in Trentino in the northern Italian region Trentino-Alto Adige/Südtirol, located about east of Trento. As of 31 December 2004, it had a population of 2,007 and an area of . It was merged with Siror, Tonadico and Fiera di Primiero on January 1, 2016, to form a new municipality, Primiero San Martino di Castrozza.
The municipality of Transacqua contains the frazioni (subdivisions, mainly villages and hamlets) Ormanico (Hermannich) and Pieve.
Transacqua borders the following municipalities: Siror (Siraur), Sagron Mis (Sagraun), Mezzano (Matzan im Taufers), Cesiomaggiore, Tonadico (Thunadich) and Fiera di Primiero (Markt Primör).