It rises from a number of springs near the Hampshire village of Baughurst, and flows to the east and then the north, to join the River Kennet to the south of Reading.

It passes a number of listed buildings and scheduled monuments, including the site of the Roman town of Calleva Atrebatum or Silchester.

The natural flow of the river is supplemented by treated effluent from two major sewage treatment works, which contribute to the poor quality of the water.

Foudry Brook rises at springs between the small villages of Heath End and Baughurst, where it is known as Bishop's Wood Stream.

It then enters a much longer culvert under Tadley Bottom, and emerges into open countryside on the east side of Bowmonts Bridge.

At the county boundary, it becomes the Foudry Brook, and at Stratfield Mortimer it passes close to the grade II listed St Mary's Church building, designed in 1869 by Richard Armstrong, but containing stained glass from the 15th and 17th centuries, as well as a Saxon stone coffin lid for Aegelwardus, who died in 1017.

Whereas the chalk is on the surface in the west of the catchment, it is covered by a layer of clay and sand to the east, where the Foudry Brook is located.

West End Brook dropped from moderate to bad in 2015, and the reasons for it not being good are mainly to do with physical modification of the channel, which prevents fish freely moving around the system, and the presence of the invasive species, the North American signal crayfish.

The brook is prone to flooding along its length, which has caused the most problems on the outskirts of Whitley, where its water voles hinder raising banks and expansion of water-meadows.

[20] In an action brought by the Environment Agency in 2002, Total Fina Elf UK Ltd was fined £54,000 for causing petrol to enter groundwater and a tributary of the Foudry Brook, from its service station in Tadley.

[22] In July 2010 a serious leak from sewage works into the Brook near Silchester killed hundreds of fish and many other organisms on a three-mile stretch.