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Cof Cymru: National Historic Assets of Wales · Wales

Cantref Water Filtration Plant

Llanfrynach, Powys, Wales

The record

Designation
Listed building, Grade II
Broad class
Water Supply and Drainage
Date of designation
28 July 2005
Locality
Nant-ddu
Town
Brecon
Community
Llanfrynach
Unitary authority
Powys
Country
Wales
Coordinates
51.82635, -3.45259
Cadw reference
84817

Slide toward Today to fade the historical sheet and see the modern map underneath.

David Rumsey Map Collection, Stanford Libraries

Shown on 5 historical map sheets, the earliest the 1636 "Cornubia : Devonia, Somersetus, Dorcestria, Wiltonia, Glocestria ..." (David Rumsey Map Collection, Stanford Libraries).

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This record in Cadw's own full report ↗

Cadw's description

Situated below the Cantref reservoir dam, on W side of A470.

Filtration plant, 1926, for the Cardiff Corporation water supply. The Cantref reservoir above was built in 1892 to the designs of J. A. B. Williams, City Engineer, and this building was added in 1926.

Waterworks, built of massive rock-faced rectangular grey limestone blocks with tooled arrises. Slate roofs overhanging at eaves. Large long two-storey range with broad roofs and metal spired ventilators on ridge. Projecting entrance gable in centre of E front. Metal 16-pane windows, mostly fixed, with tooled ashlar lintels and sills, the lintels chamfered and stopped. Raised plinth and eaves band, the facade divided by raised piers, with plinth and eaves band broken forward over. The wings have broad outer angle piers, five bays each with a triple 16-pane window above a blocked lunette, the lunettes with stone voussoirs and tooled sills and an inner pier pierced by a loading door above a blocked window.
The centre projection has a broad pedimental gable with rock-faced band carried across from eaves, small roundel and plain bargeboards. Three bays, outer ones recessed with 16-pane window each floor, centre bay is narrow with window over doorcase of especially massive detail in brown sandstone. Rock-faced cornice in single block, rock-faced to front, chamfered below. Rusticated side piers. Doorcase frames doorway of smooth sandstone with massive lintel inscribed 'Cardiff Corporation Waterworks Cantref Roughing Filter MCMXXVI' over double panelled doors. One-bay sides with 16-pane sash window each floor. All windows of centre projection have been replaced in uPVC.
S end has broad gable with small roundel light, radiating voussoirs, stone band below gable, broad recessed centre with triple 16-pane windows over a blind lunette, and side bays with a single 16-pane window at upper level.
The N end is treated as a tower with broad outer piers and parapet with taller piers framing. The E side has a triple window over two blocked windows. The broad N end has similar three-light to first floor, and W side has a similar upper window.
The rear W has five-bay wings framing a centre projection, here with flat roof carrying large iron water tank. The left wing has five bays of triple windows to upper floor, no lunettes below. The centre projection has raised piers at angles and heavy rock-faced top cornice. N side has two windows above a lunette. W side is of three bays with lunette to lower floor of outer bays, centre arched doorway in high plinth of centre bay. Added concrete first floor link above to modern building to W. Right wing has similar five bays, but the first three obscured by a flat roofed single-storey range.

Not inspected.

Included for its special interest as a very large water-industry building of definite character notably its finely worked masonry.

Nearby in the register

Other entries of the same register within about three miles of this one, by straight line.

Designated Historic Asset GIS Data, The Welsh Historic Environment Service (Cadw), 2026-09-07, licensed under the Open Government Licence http://www.nationalarchives.gov.uk/doc/open-government-licence/version/3/ Cadw, the Welsh Historic Environment Service · Open Government Licence v3.0
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