11.107 Much of the territory's supply comes from relatively unpolluted upland resources and standard treatment comprising coagulation with alum and lime followed by rapid gravity filtration, sterilisation with chlorine, acidity correction with alum and fluoridation effects the required degree of purification.
Special additional treatment and quality surveillance facilities are incorporated at certain stations, particularly the largest treatment works at Sha Tin which has a capacity of 175 m.g.d., where a proportion of the raw water is derived from poorer quality lowland resources.
11.108 The quality of water stored in Plover Cove, which was opened for licensed angling for the first time in September, continued to be highly satisfactory but an increase in illegal netting of stocked fish gave cause for concern.
11.109 Salt water flushing supplies are chlorinated at intakes to suppress marine growths in pipelines and to prevent a deterioration of quality in distribution systems.
11.110 Average dosages and total consumption of principal chemicals used in water treatment are shown in Appendix CC.
Quality of Supply
11.111 Generally the supply is classified as soft and low to moderate in total dissolved solids content. Average quality continued to be markedly better than the target chemical and bacteriological standards recommended by the World Health Organisation. Information on principal water quality characteristics is given in Appendix CC.
11.112 Restrictions in September - October caused an expected increase in complaints of dirty or discoloured water due to disturbance of harmless rusty deposits in mains, but although the public was advised to boil drinking water during this period the bacteriological quality of tap water was little affected.
11.113 Routine water quality monitoring in the distribution system was reorganised and expanded to include certain important chemical aspects as well as bacteriological purity and the entire supply network is now considered to be under a satisfactory degree of surveillance.
11.114 In order to discourage the use of galvanised iron pipes in centralised hot water systems, which have given rise to corrosion and discoloured water problems, the Buildings Ordinance Office — at this Office's request — circulated a 'Practice Note for Authorised Persons' advising the use of copper or stainless steel pipes for such systems.
11.115 In collaboration with the Architectural Office investigations were begun to test the effect of a chemical corrosion inhibitor in existing hot water systems at certain Government buildings.
11.107 Much of the territory's supply comes from relatively unpolluted upland resources and standard treatment comprising coagulation with alum and lime followed by rapid gravity filtration, sterilisation with chlorine, acidity correction with alum and fluoridation effects the required degree of purificatio
Special additional treatment and quality surveillance facilities are incor- porated at certain stations, particularly the largest treatment works at Sha Tin which has a capacity of 175 m.g.d., where a proportion of the raw water is derived from poorer quality lowland resources.
11.108
The quality of water stored in Plover Cove, which was opened for licensed angling for the first time in September, continued to be highly satisfactory but an increase in illegal netting of stocked fish gave cause for concern.
11.109 Salt water flushing supplies are chlorinated at intakes to suppress marine growths in pipelines and to prevent a deterioration of quality in dis- tribution systems.
11.110 Average dosages and total consumption of principal chemicals used in water treatment are shown in Appendix CC.
Quality of Supply
11.111 Generally the supply is classified as soft and low to moderate in total dissolved solids content. Average quality continued to be markedly better than the target chemical and bacteriological standards recommended by the World Health Organisation. Information on principal water quality characteristics is given in Appendix CC.
11.112
Restrictions in September - October caused an expected increase in complaints of dirty or discoloured water due to disturbance of harmless rusty deposits in mains, but although the public was advised to boil drinking water during this period the bacteriological quality of tap water was little affected.
11.113 Routine water quality monitoring in the distribution system was re- organised and expanded to include certain important chemical aspects as well as bacteriological purity and the entire supply network is now considered to be under a satisfactory degree of surveillance.
11.114 In order to discourage the use of galvanised iron pipes in centralised hot water systems, which have given rise to corrosion and discoloured water problems, the Buildings Ordinance Office
-
at this Office's request
-
circulated
a 'Practice Note for Authorised Persons' advising the use of copper or stainless steel pipes for such systems.
11.115 In collaboration with the Architectural Office investigations were begun to test the effect of a chemical corrosion inhibitor in existing hot water systems at certain Government buildings.
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