Water Quality Control Section
7.12. The exploitation of new and comparatively polluted resources to meet the increasing demand for water necessitated not only the installation of more elaborate filtration works but also closer control of the processes of purification. To meet this need a water quality control section was formed which is responsible for all matters concerning treatment and quality control of the Colony's water supplies.
7.13. A fully equipped laboratory was set up at the Sha Tin Treatment Works for carrying out chemical and bacteriological examination of water samples and investigating various problems connected with the water industry in general.
7.14. The bacteriological quality aimed at for the final supply throughout the distribution system is the absence of coliform organisms in samples of a hundred millilitres. In fact 96.4 percent of 355 samples taken at service reservoirs and 93.6 percent of 1,132 samples from consumers' taps conformed to this standard. Dirty storage tanks and defects in the internal plumbing systems were the main causes of sub-standard tap samples. In each of these cases after remedial works were carried out subsequent samples proved satisfactory.
7.15. The standard of chemical quality of supply was satisfactorily maintained and fluoridation was continued at levels of 0.7 parts per million during the summer months (May to October) and 0.9 parts per million during the winter months (November to April).
7.16. In addition to the supervision of treatment at all filter stations and the routine monitoring of water quality throughout the supply system, the Section assisted in evaluating the quality of new resources particularly in connexion with the Plover Cove and North West Water schemes, and in planning the Tai Po/Sheung Shui Treatment Works. A variety of work connected with water quality and treatment was undertaken for a number of other Government departments, H.M. Forces, and commercial firms.
General
MECHANICAL AND ELECTRICAL DIVISION
Chief Engineer:
J. M. PETTIGREW, A.M.I.Mech.E.
7.17. The division continued to operate and maintain all waterworks plant and equipment, as well as to install all new waterworks plant and equipment other than that for works supervised by consulting engineers.
66