The Ub originates from the Vlašić mountain in Podgorina region of west Serbia, near the village of Kasapo.

The villages located in the upper section of the river's flow are Družetić, Pambukovica and Čučuge, where the Ub slightly turns to the north, passes through the villages of Tvrdojevac and Zvizdar, and the small town of Ub, named after the river.

The Ub continues to the north and meets the Tamnava river near the village of Šarbane.

The river drains an area of 274 km², belongs to the Black Sea drainage basin and it is not navigable.

The dam will be located 21 km (13 mi) upstream from the town of Ub, on the territory of the villages Pambukovica, Raduša and Gola Glava.