42
HONGKONG LEGISLATIVE COUNCIL
Questions Regarding The Water Supply
HON. MR. H. W. BIRD, in accordance with notice previously given, asked-
"
'In view of the widespread want of confidence in the purity of the water supply of the Colony, will the Govern ment give reassuring information on the following points :---
1. How does the purity of the water compare with that of London (or any large British town) and what is the exact comparison from a bacterio- logical and clinical point of view? 2. Is the water analysed chemically and examined bacteriologically at regular intervals at the following points? (1) Nullahs entering reservoirs. (2) Reservoirs.
(3) Filter beds.
(4) Actual tap supply.
If so could the exact results be stated for the water supplied from Pokfulam Reservoir during the last few months? Is it a fact that the water from Pokfulam Reservoir is used at such a rate that it is not stored for a proper length of time? 3. Is there any question whatever of the filter beds being overworked in order to cope with the amount of water re- quired?
4. If the filter beds are overworked or are not supplying a really high quality water, is it not possible to use some more efficient methods of filtration?
5. If filter beds are working efficiently
what is the reason of
(1) the present brown coloured water
supplied from taps?
(2) the addition of chloride of lime? 6. Is there any necessity to boil and filter the water supplied from our taps? If so, why?
7. What arrangements are made for the correct addition of chloride of lime, and is it satisfactory when the water tastes of chlorine?
THE COLONIAL SECRETARY replied | 1. The standard of purity in force in Hongkong was only adopted after correspondence with eminent special-
ists
in England. Particulars of British towns are not available.
2 (1) The answer is in the negative.
(2), (3) and (4) The answer is in the
affirmative.
Early in July a report was received from the Bacteriologist that the Pok- fulam water was below standard, pre- vious reports having been very satis- factory. Additional chlorination was at once undertaken, and more recent tests show that the water is now above standard.
During the rainy season it is im- possible to state what storage period is obtained from any reservoir owing to the new water mixing with the stored water.
3. In the summer time on full supply the filter beds have to be worked at an undesirably high speed. The pre- sent restrictions in districts supplied from Pokfulam are due to the neces- sity for the relatively slower filtra- tion of Pokfulam water.
4. Slow sand filtration as in operation in Hongkong is the general type of filtration in use in London and most large English towns and is consider- ed the most suitable type under cer- tain conditions. Large extensions to the Hongkong filter beds are at pre- sent under construction and tenders have been invited for the extension of the existing filter beds at Kowloon and the supply of fast gravity filters for both Hongkong and the mainland.
5. (1) Some of the water being dealt with at present is of an excep- tionally muddy character carrying very finely divided kaolin in sus- pension. To eliminate entirely this fine silt would require very slow filtration or probably precipita- tion.
(2) As indicated in the answer to
question No. 3 the capacity of the present filter beds is insufficient to meet the increasing demands of the Colony, and a speed of filtra- tion which would ordinarily be considered undesirable is render.. ed necessary. Chlorine is added, as in London, in order to sterilise the water, without so far as can be avoided giving it a disagree- able taste.