Rising on Chelburn Moor (south of Todmorden in the Pennines), the river flows south through Littleborough towards Rochdale where it is joined by the River Beal at Belfield, and the River Spodden from Whitworth. Turning west it runs past Heywood and Bury before meeting the River Irwell just to the east of Radcliffe.
The Domesday Book records the name of Rochdale as Recedham, formed from Old English reced "hall", and ham "homestead". The name of the river is a back-formation from this Old English name. With time, the town's name changed to Rachedale and eventually Rochdale. The name of the river Roch is //, with a long o. The name of the town, however, is pronounced /ˈrɒtʃdeɪl/, with a short o.
The river has been culverted in Rochdale town centre since the early 20th century. This was built by the joining together of seven bridges to form one large bridge, making it one of the widest bridges in the world. Maintenance work was carried out on the bridge in the 1990s and the river was uncovered temporarily. In 2015 work began on opening the bridge again in a multimillion-pound project. On Boxing Day 2015, following heavy rain, the Roch burst its banks causing flooding in the town centre.
Moving upstream from the Irwell confluence, the tributaries include the following:
|Next confluence upstream||River Irwell||Next confluence downstream|
|Woodhill / Kirklees Brook (West)||River Roch||River Croal (West)|