Flat Holm Victorian Rain Water Catchment

Cadw's description

Summary description and reason for designation

The monument comprises the well preserved remains of a Victorian rain water catchment, which was designed to collect water for use by the military garrison that occupied Flat Holm Island in the Bristol Channel. It is located on a steep east-facing slope on the south-east corner of the island between Dripping Cove and Lighthouse Point. The catchment was constructed from red ceramic brick tiles and enclosed by a low masonry wall surmounted by half round copings. The structure slopes steeply to the east and north, and was designed to collect rainwater and direct it into an adjacent rock cut cistern via a drain and culvert in the lower eastern corner. The Victorian gun batteries were built on Flat Holm between 1866-71, and the water catchment must have been built at the same time or soon afterwards to provide water for the garrison. A War Department boundary stone is located adjacent to the inner face of the upper, western boundary wall.

The monument is of national importance for its potential to enhance our knowledge of the development of water supply and management in a military context, and the State’s response to controlling communicable diseases as scientific understanding progressed during the late nineteenth century. It was common practice for the War Department to collect rain water from the roofs of casemates and buildings, but a different solution was required on Flat Holm owing to the lack of such opportunities. The use of a water catchment was unique in Wales, and rare in the UK. The monument is well-preserved and retains significant archaeological potential, with a strong probability of the presence of associated archaeological features and deposits, relating to chronology, building techniques and architectural detail. The water catchment was functionally inter-dependent with the barracks and gun batteries elsewhere on the island and possesses important group value with these designated assets.