Claremont Square Reservoir

The Claremont Square Reservoir is a covered reservoir built in 1855, designed by John Murray, in response to the Metropolis Water Act of 1852. This Act was prompted by the cholera epidemic of 1846 and mandated that all London reservoirs be covered. The reservoir occupies the site of a previous open reservoir, the Upper Pond of 1709, which was part of the New River system dating from 1608-1613, although no remains of this earlier structure are visible.

The reservoir is a square structure approximately 80 metres across, constructed primarily of stock brick with Yorkstone floor slabs. It is situated entirely within Claremont Square and largely obscured by vegetation, including tall grass covering the sloping sides and a low brick parapet. The roof is also grass-covered and features rows of iron ventilation pipes and eight circular equipment hatchways with domed metal covers. A slab-covered entrance on the east side provides access via two flights of stone stairs with an iron handrail, descending to a floor approximately eight metres below ground level.

Inside, the reservoir is divided into eleven north-south bays by partition walls that support the barrel-vaulted ceiling. These walls are pierced by ten narrow, segmental-arched apertures, and braced by two cross walls over each bay. The outer wall is slightly battered to counteract the load of the earth mound surrounding it. As a header tank supplying Islington and the West End by gravity, the reservoir contains no pump equipment. A large iron bore pipe with a gate valve and control rod is located on the south side for inlet access. Similar pipes with control mechanisms are situated at the southwest, northeast, and northwest corners. The pipes and associated equipment, dating to 1855, stand on raised Yorkstone slab floors, chosen for their resistance to water currents. Flagstones line a shallow, two-metre wide channel running across the southern end of the basin to a drain in the west wall, used for flushing and cleaning. The remainder of the floor consists of brick, forming slightly concave channels at the foot of each bay. Additional outlet pipes set into the west wall and some associated rendering are later additions to the original 1855 structure. Plans from 1855 are held by Thames Water, and an illustration of the reservoir under construction was published in "The Engineer" in October 1948 (reprinted 1954).