The deliberate ornamentation and stylisation in the individual designs of each reservoir demonstrates the intention of the Board to produce landmark structures which harmonised with their immediate environment. Drummoyne was one of two reservoirs built with an attached tower and was the only reservoir in the group to feature a tower as a deliberate ornament. It is now the only reservoir with its tower surviving. The combined tower and reservoir is a fine, well-designed Federation Free Classical structure and a local landmark which complements the architectural character of the vicinity. The provision of the tower is associated with Sir Thomas Henley, a prominent local identity and politician who was also a member of the Board of Water Supply and Sewerage and who had been instrumental in the provision of these Reservoirs. Drummoyne Reservoir was listed on the National Trust of Australia register in 2000, the City of Canada Bay Heritage Schedule and the Heritage Act - s.170 NSW State agency heritage register in 2000. The Reservoir was listed on the New South Wales State Heritage Register on 15 November 2002 having satisfied the following criteria. The place is important in demonstrating the course, or pattern, of cultural or natural history in New South Wales. The Drummoyne Reservoir is one of a group of four water supply service reservoirs which together represent an important technological development in the use of reinforced concrete for reservoirs in NSW. The group of four elevated steel and reinforced concrete reservoirs is the first group of large (over 0.5 Ml) water storage reservoirs built above ground level as part of the metropolitan water supply system, allowing gravity reticulation to the highest land areas. This was a major improvement in supply and an important developmental stage in the provision of water supply in Sydney. Drummoyne Reservoir provides evidence of the extent of urban development in its service area at the time of its construction, both by the selection of its locality and its size. Drummoyne Reservoir's history of usage, leading to its current redundancy within the Water Supply system, is illustrative of the growth of Sydney and the corresponding development of the water supply network over this period. Drummoyne Reservoir provides evidence of the cultural philosophy prevalent at the time of its construction, whereby there was a conscious effort by public authorities to integrate the appearance of mundane, functional structures into the aesthetic context of the community. This is in contrast to the late twentieth century trend towards cost-based "functionalist" design for such structures. The design of Drummoyne Reservoir illustrates the Victorian and early twentieth century attitude that the provision of public infrastructure was evidence of cultural and material progress and that the arrival of such structures within a community was a matter of achievement.