Foel Valve Tower is the extraction point for all water in the Elan Valley Water Scheme (nprn 96459). It marks the start of the Elan Aqueduct (nprn 95469), of which Foel Tunnel is the first section. It is a round valve tower constructed of brown faced stone. The upper stage has a copper dome with a low lantern and weathervane and 7 round arched windows. It is said to contain original operating machinery.

Reference: Cadw listed buildings database.
B.A.Malaws, 25 November 2003.