It rises at 1,213 feet (370 m) above mean sea level near the village of Treborough, in the Brendon Hills, and flows into the Bristol Channel in the port town of Watchet.

On its course it flows through the civil parishes of Treborough, Luxborough, Withycombe, Old Cleeve, Nettlecombe, Williton and Watchet, and through the settlements of Pooltown, Kingsbridge, Roadwater, Torre, Washford and Watchet.

The Environment Agency defines two waterbodies for the catchment area.

The Washford - Lower waterbody comprises the area up to Tacker Street, just upstream of Roadwater, whilst the Washford - Upper waterbody comprises the area above that point.

As of August 2023, the Washford - Lower waterbody had a moderate ecological status, whilst the Washford - Upper had a poor ecological status.