at Sha Tin Treatment Works is fully equipped to carry out chemical and bacteriological examinations of water samples and an additional subsidiary laboratory was set up in Kowloon to deal mainly with bacteriological samples taken locally. A total of 10,024 samples were tested of which 3,058 were for bacteriological examination.
7.56. The supply to all urban areas is fully treated by coagulation, filtration, chlorination and fluoridation and the water is classed as very soft (average hardness 24 parts per million expressed as calcium carbonate) and low in mineral salts content.
7.57. Fluoridation was continued, the levels aimed at being 0.7 part per million during summer months (May to October) and 0.9 part per million during winter months (November to April). The average level achieved in practice during the year was 0.77 part per million compared with the nominal average of 0.80 parts per million.
7.58. Much importance is attached to achieving a high degree of bacterial purity of supply throughout the distribution system, the standard aimed at being complete absence of coliform organisms in 100 millilitres of each sample examined. Out of 1,296 samples taken from service reservoirs (all of which are tested regularly) 99.4% conformed to this standard. Random samples are also taken from consumers' premises and 98.8% of 693 samples from taps connected directly to mains were satisfactory, whereas in the cases of 536 samples taken from taps fed from private storage tanks 94.8% were free from coliform organisms, the larger percentage of sub-standard samples in this category being largely due to the dirty condition of some tanks.
7.59. Considering the size of population served, complaints made concerning the quality of supply were relatively few. All were investigated and where appropriate check samples were taken. Out of 160 such notifications received 84% were of dirty or discoloured water, while objectionable taste or odour accounted for a further 14%.
7.60. The Section undertook a great variety of other work including investigations and advice in connexion with the Plover Cove Water Scheme, the Water Resources Survey project and the planning of new treatment works. A total of 447 analyses were also carried out for other Government departments, the armed services, commercial firms and the general public.
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at Sha Tin Treatment Works is fully equipped to carry out chemical and bacteriological examinations of water samples and an additional subsidiary laboratory was set up in Kowloon to deal mainly with bacteriological samples taken locally. A total of 10,024 samples were tested of which 3,058 were for bacteriological examination.
7.56. The supply to all urban areas is fully treated by coagulation, filtration, chlorination and fluoridation and the water is classed as very soft (average hardness 24 parts per million expressed as calcium car- bonate) and low in mineral salts content.
7.57. Fluoridation was continued, the levels aimed at being 0.7 part per million during summer months (May to October) and 0.9 part per million during winter months (November to April). The average level achieved in practice during the year was 0.77 part per million compared with the nominal average of 0.80 parts per million.
7.58. Much importance is attached to achieving a high degree of bacterial purity of supply throughout the distribution system, the standard aimed at being complete absence of coliform organisms in 100 millilitres of each sample examined. Out of 1,296 samples taken from service reservoirs (all of which are tested regularly) 99.4% conformed to this standard. Random samples are also taken from consumers' premises and 98.8% of 693 samples from taps connected directly to mains were satisfactory, whereas in the cases of 536 samples taken from taps fed from private storage tanks 94.8% were free from coliform organisms, the larger percentage of sub-standard samples in this category being largely due to the dirty condition of some tanks.
7.59. Considering the size of population served, complaints made concerning the quality of supply were relatively few. All were investi- gated and where appropriate check samples were taken. Out of 160 such notifications received 84% were of dirty or discoloured water, while objectionable taste or odour accounted for a further 14%.
7.60. The Section undertook a great variety of other work including investigations and advice in connexion with the Plover Cove Water Scheme, the Water Resources Survey project and the planning of new treatment works. A total of 447 analyses were also carried out for other Government departments, the armed services, commercial firms and the general public.
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