Lake Vyrnwy Straining Tower and approach bridge

The Lake Vyrnwy Straining Tower and its approach bridge are a late 19th-century structure, designed in a romantic style said to be influenced by the medieval castle of Chillon, near Lake Geneva, although more closely resembling the work of architect William Burges. The tower rises to a height of 52 metres, with approximately 35 metres typically visible above the water level. It is constructed from mass concrete with a facing of local rubble. A prototype form of reinforced concrete was used at gallery level, featuring continuous steel wire mechanically wound onto cast-iron chairs within the wall. The tower is circular, with a machicolated parapet and a pierced balustrade to the wall-walk. The upper portion is octagonal, featuring two-light openings to alternate faces, and is crowned by a swept pyramidal roof including gabled dormers with small panes of glass. On the south-east side, a circular stair tower projects from the main tower above the waterline, featuring a cross-frame windowed bellcote and a steep conical roof. Both roofs are covered in copper sheeting on a timber frame, reportedly made of Indian oak, and are decorated with weathervanes and finials. Below the parapet, the engine room is lit by shouldered lancet windows, while two-light medievalist windows illuminate the washing floor, where the tower is entered; a square-headed doorcase has a small-pane overlight.

The tower is connected to the shore by a stone bridge composed of four segmental arches, with parapets featuring dressed coping. Steps lead up to road level at the shore end, where massive gate piers support a pair of wrought iron gates.

Beneath the waterline, the tower’s base contains space for three strainers, each nearly 8 metres high, alongside adjustable inlet pipes which can be raised or lowered externally to ensure clear water is drawn near the surface of the lake. Entry to the tower is at washing-floor level, where the strainers are raised for cleaning by sprays within iron casings. An inspection platform exists below this level, with trays to collect the cleaning water. A spiral staircase leads to the engine room, which retains its original equipment. The engine room’s centrepiece is a two-cylinder hydraulic engine by Glenfield Co. Kilmarnock, installed in 1889, powered by a reservoir on a nearby hill providing a 35-metre head. This engine operates three large hydraulic rams to lift the strainers and two further rams to raise and lower the inlet pipes. The domed roof of the engine room is of shuttered concrete with wrought iron ribs, and originally included a central lantern with a railed gallery. The hydraulic rams pass through the dome to a floor above. That floor contains an octagonal room with access to the wall-walk, which provides access to the winches that operate the inlet pipes, housed beneath a gabled hood; the bellcote is also at this level. A cantilevered timber staircase then rises to the loft, where the roof structure is supported on a cross-frame base with a pendant.