Disused Reservoir

The disused reservoir, built in 1855, is an underground structure that reused bricks from an earlier House of Correction located to the south of the castle grounds. It was roofed over in 1886. Externally, the reservoir features brick walls enclosing a triangular site. Along Pewley Hill, there is a large wall made of red brick with grey headers in English bond, likely using reused bricks, topped with a stepped panelled parapet in brown brick dating from around 1885. The corner of the wall is constructed in header bond. On Oxford Terrace, the wall stands about 9 feet high and is made of early 19th-century bricks in Sussex bond, incorporating one circular iron tier. The opposite elevation features 20th-century brickwork. Inside, the reservoir has a boat-shaped structure approximately 30 feet deep, lined with reinforced concrete, and features a six-bay brick barrel vaulted roof supported by angled iron supports on brick padstones. This reservoir is noted for its unusual shape and early use of reinforced concrete, as referenced in N.C.C. Barrell's "The History of the Guildford Waterworks," 2nd edition, 1951.