The headwaters of the river are in Suco Uacala [de], Baguia administrative post, Baucau municipality, and the adjacent Sucos Baricafa [de], Luro administrative post, and Caenlio [de], Iliomar administrative post, both of which are in Lautém municipality.

From there, it flows southwestwards along the border between Lautém to the southeast and Baucau to the northwest, and then, from the tripoint between Baucau, Lautém and Viqueque municipalities, southwards along the whole of the border between Lautém to the east and Viqueque to the west, until it empties into the Timor Sea.

[12] The main tributaries of the river, in order of entrance, are as follows:[7][8][9] The catchment or drainage basin of the river is one of Timor-Leste's 10 major catchments,[45] and is approximately 489 km2 (189 sq mi) in area.

[46]: 2, 52 Timor-Leste has been broadly divided into twelve 'hydrologic units', groupings of climatologically and physiographically similar and adjacent river catchments.

[46]: 9, 52, 58 [47] Media related to Irebere River at Wikimedia Commons