The torrent has its source between the municipalities of Uggiate Trevano and Faloppio (from which it takes its name) and flows between Lombardy and Canton Ticino, where it joins the Breggia torrent at the Brogeda customs point. Its waters therefore flow northwards, rather than southwards, as almost all the watercourses in the area. Until a few decades ago, the stream fed the numerous mills operating in the valley that gave it its name, the Val Mulini.