Piz Buin Pitschen separates two glacial valleys, the Ochsenthaler Glacier on the north and La Cudera on the southwest of the mountain. While the Ochsenthaler Glacier forms the origin of the River Ill, which first fills the Silvretta Reservoir at the Silvretta High-Alpine-Road and later flows into the Rhine (North Sea). South of Piz Buin Pitschen the water flows in the Inn, which empties into the Danube (Black Sea).