The Wahroonga Reservoir is a heritage-listed reservoir located at 1678 Pacific Highway and Woonona Avenue in the Sydney suburb of Wahroonga in the Ku-ring-gai Council local government area of New South Wales, Australia. It was designed and built by the Metropolitan Board of Water Supply and Sewerage in 1915. It is also known as Wahroonga Reservoir (Elevated) (WS 0124). The property is owned by Sydney Water, a State-owned statutory corporation of the Government of New South Wales. It was added to the New South Wales State Heritage Register on 18 November 1999. History Northern Suburbs supply When the Board of Water Supply and Sewerage took over from Sydney City Council in 1888, the only supply to the northern suburbs was by a submarine main from Dawes Point to Milsons Point, taking water by gravitation from Paddington Reservoir. The level of Paddington Reservoir limited supply to the lower areas of Northern Suburbs. In 1888, in order to overcome this problem, the Board erected a pumping station in Junction Street, , with two storage tanks in the grounds of St. Thomas' Church, to meet demand for the higher parts of North Sydney. The plant was dismantled in 1892, the pump being transferred to Carlton and the tanks to Wahroonga (not extant). The above submarine main was abandoned in 1917. In 1892 the Ryde Pumping Station was commissioned, supplied by mains from Potts Hill (via Rookwood Cemetery, along the Concord Peninsula and attached to the 1889 railway bridge at Meadowbank), with reservoirs at Ryde Pumping Station (disused 1930) and Ryde Hill and then by mains to a pair of reservoirs at Chatswood (previously constructed in 1888). With increasing population of the North Shore, brought about by the construction of the railway, new storage reservoirs were required. The tanks, originally at North Sydney, were transferred to Wahroonga in 1896. A steam powered pumping station was erected at Chatswood in 1895 for the supply of Wahroonga. A new steel surface reservoir was constructed at Wahroonga in 1898 (Wahroonga Reservoir No. 1 WS 123). From Wahroonga the main from Chatswood extended to Hornsby, with a branch to Thornleigh and Beecroft. The mains from Chatswood to Wahroonga had deteriorated by 1905, necessitating new direct mains from Ryde to Wahroonga, and from Chatswood to Pymble to connect to former. Wahroonga Reservoir (Elevated) WS 0124 was erected in 1915. A main to Mobbs Hill was constructed in 1916. It