Filter House at Pontsticill Water Treatment Works

Filter House at Pontsticill Water Treatment Works is an original L-shaped building consisting of two wings connected by a corner tower. It is constructed of brick rendered in roughcast and features a Welsh slate roof with a copper dome on the tower. The main wings have ten-pane metal-framed windows beneath dentilled eaves and a large semicircular window with decorative voussoir-type mouldings in the gable ends, which is now visible internally in the extended range. The tower, which contains a staircase, is four storeys tall and has larger metal-framed windows on the lower levels, smaller windows on the upper storey with some billet moulding, and is topped by a green copper dome. The extended range to the east is slightly smaller and has a smaller tower that lacks the dome.

The roof is supported by a network of bolted steel trusses and is lined with painted timber. The filter beds are made of concrete, each equipped with a valve, and there is a railed walkway with a terrazzo floor. At the lower level, there is filter machinery for each bed, with box tanks lined with white and brown tiles. The former outer wall, which had large round-headed steel-framed multi-pane windows, now serves as an internal wall for a new development. Near the staircase, there is a tiled water sampling point.