The Flumini Mannu is a river in southern Sardinia, Italy.

Its springs are located in the hills east of Sardara. It flows into the Stagno di Cagliari after a course of 42.14 kilometres (26.18 mi). The river's main tributaries are the Riu Bellu and the Rio Sitzerri, which for most of the basin of Monte Linas massif's waters.