30
REVIEW
physical impossibility of providing space for pipes under the street to supply buildings further afield. When redevelopment takes place new service connexions have to be made; 20 storey buildings, re- placing four storey ones, demand enlarged services and soon new trunk mains become necessary. The constant digging up of the roads consequent on redevelopment is an all too familiar feature of Hong Kong life.
A city is built on its sewers and early in the history of the Colony there was talk of the need for better drainage to protect public health. Since 1847, when 2,440 yards of city drains were laid, up to the present time, it has been merely a question of keeping ahead of development. This has not been easy but today nearly all built-up districts have water-borne drainage. In recent years it has been necessary to give increasing attention to the treat- ment of sewage at the main outfalls in order to lessen harbour pollution; also to the enlargement of existing trunk services to deal adequately with the very high population densities, particularly in Kowloon. Excessively high rainfall over a few hours—the highest on record for any 24 hours is 27.85 inches in May 1889—is a potential source of flooding and any development of low-lying land, particularly the reclamation of river estuaries, involves the construc- tion of large storm-water drains or culverts; the work now in hand in the market town of Yuen Long is a case in point. In the early days it was usual to solve such problems by large open channels or nullahs running down the centre of main roads. Many of these have now been culverted or decked, not only to improve drainage conditions but also to effect a much needed street improvement.
Sir Charles Elliot's notice of 1st May 1841 required, inter alia, that ‘no run of water be diverted from its course' and Sir Henry Pottinger directed the 1842 Land Committee to 'select the most eligible spot with a running stream of good water' to provide a 'watering place for shipping'. In 1851 five wells were sunk for the city water supply and 20 years later the first reservoir at Pok Fu Lam was completed. Thereafter, as for other civil engineering serv- ices, it has been a constant race against population and development with periods of adequacy and points of shortage. It has been necessary to import water three times during the Colony's history —in 1903, 1929 and today. Geographical and climatic conditions make it necessary to store enough water for a seven-month dry