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with impounded water being conveyed through a 2.2km-long 2.5m-diameter tunnel, mainly in granite, and by a 5km-long conduit winding along the northern shore of the Island beneath Bowen Road to the first two slow sand filter beds above the city, and thence into the service reservoir located at a lower level. The distribution system involved laying, between 1890 and 1892, some 30 kilometres of 75-350mm-diameter cast-iron mains together with the installation of a system of fire hydrants. Major fung shui problems were encountered during the tunnelling works, rumour being that children were to be selected for burial alive to ensure success; fortunately no ritual sacrifice was needed!
On an uncontoured 1895 version of Collinson's plan (1845), there is an interesting feature clearly marked “overhead tram" extending 2.3 kilometres between Quarry Bay and Quarry Gap. It seems likely that it would have been used to transport materials and, perhaps, workmen associated with the early Tai Tam reservoir works. As part of the Tai Tam scheme a further small high-level reservoir at Wong Nei Chong was completed in 1899. Around this time the Braemar reservoir (now Choi Sai Woo Park) and further smaller reservoirs near Quarry Bay were built, primarily to meet the needs of the large commercial Tai Koo sugar refinery and dockyard complex.
With the population already rising to about half a million, three further concrete dams within the Tai Tam valley, the largest Tai Tam Tuk being 50m high, and associated reservoirs were completed between 1904 and 1917. The upper (42m high) and reconstructed lower (20m high) concrete dams, the latter being previously a privately-owned dam built in 1890 for a paper works, impounding the Aberdeen reservoirs were later finished in 1931 and 1932 respectively, thus completing the last economical water storage development on the Island.
After the turn of the century engineers were already looking to the New Territories to increase the supply of water for Kowloon, which had hitherto been dependent on two wells located to the north of Yau Mai Tei. As a result, the 35m-high concrete dam for the Kowloon reservoir was completed in 1910 and three further reservoirs in the vicinity were completed during the period 1925-1931 by which time the population was already approaching a million. A commercial reservoir was also built early this century to the south of Lung Wo Tsuen to provide water for Rennie's cotton factory at Junk Bay.