Monks Brook is a river in the English county of Hampshire. It is a tributary of the River Itchen, which it joins at a medieval salmon pool in Swaythling. The brook is formed from seven streams that rise in the chalky South Downs, with the official source of Monks Brook being known as Bucket's Corner. Monks Brook drains a clay catchment of 49 square kilometres (19 sq mi). The brook is designated a main river, which means the operating authority for managing it is the Environment Agency, not the local government authorities for the areas through which the river runs.