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extensively purified but require sterilization before entry to fresh water and subsequent use for either bathing or drinking. If chlorination were to be adopted in Hong Kong, the cost of materials alone would amount to something like $10 million a year.
The Director of Marine has informed me that he knows of no port in the world in which special measures are taken to control the discharge of sewage from shipping other than when in dry dock. However, the Port of London Authority has been considering the matter in view of the limited movement of tidal water in their docks. The position differs in Hong Kong in that the harbour possesses a strong tidal stream. It is considered moreover that the degree of contamination of the harbour water by large vessels is small compared with the discharge from sewers, from sampans and other licensed and unlicensed small craft.
DR. LEE: From the medical point of view, Mr. Chairman, may I ask the Vice-Chairman whether it is not medically sound to have sewage chlorinated before it is discharged into the harbour?
ACTING DEPUTY DIRECTOR OF MEDICAL AND HEALTH SERVICES: Mr. Chairman, I think this question revolves round the question of whether this discharge is dangerous to the public health of the people. There is a potential danger to health where sewage pollutes sea water on account of the possible presence of organisms of typhoid and dysentery. In Britain in 1960 the Committee of the Public Health Laboratory Service on Sewage Contamination of Coastal Bathing Water stated that the risk of infection by pathogenic bacteria as a result of bathing in sea water was trivial, with the possible exception of those beaches termed as aesthetically revolting. Conditions are different here, in that certain diseases such as typhoid and dysentery are far commoner and the chances of acquiring infection proportionately greater. However, in Hong Kong there has been no evidence so far that sea bathing plays a part in the spread of enteric diseases.
DR. LEE: Is the Vice-Chairman aware that a large area of Hong Kong is served only by a conservancy system and also that with those areas being served by a sewerage system, does he not agree that the degree of pollution in the harbour will be much greater, since we have pollution now in 4 out of 7 specimens so far submitted? Does he not also agree that the pollution will be far greater as the population growth increases?
ACTING DEPUTY DIRECTOR OF MEDICAL AND HEALTH SERVICES: I think I must say "Yes", Mr. Chairman. With the increase in population and more discharge of sewage into the harbour, there will be an increase in the pollution of harbour water, but, of course, there is a strong tidal stream in the harbour which serves to disperse the sewage which enters these waters.
DR. LEE: Does the Vice-Chairman not agree that one or two outfalls might be chlorinated and from experiments conducted, that information will be gathered?
ACTING DEPUTY DIRECTOR OF MEDICAL AND HEALTH SERVICES: My friend the Director of Public Works has already indicated that if this measure were to be adopted it would result in the expenditure of a very large sum of money. Quite apart from this, I am not sure whether it would be suitable or whether it would be a reasonable proposition to undertake an experiment on chlorinating the sewage entering the Colony's waters. Perhaps the Director of Public Works might care to advise us on that point?
DIRECTOR OF PUBLIC WORKS: I would only be prepared to advise if I have got the question in writing. I am not prepared to express an opinion on Dr. LEE's question which I did not fully understand.
DR. LEE: Is the Director of Public Works' lack of understanding of the question purposeful or is he trying to be ignorant? I am sure that sewage treated by chlorination is a very sound and practical proposition, but to quote the figure of $10 million in a community like Hong Kong whose income runs to billions, is only a drop in the bucket. In other big cities of the world they have such things as sewage farms. I wonder whether the Vice-Chairman is prepared to quote some practical figures on sewage farms so used in other big communities?
DIRECTOR OF PUBLIC WORKS: Mr. Chairman, perhaps I should show my willingness to try and help Dr. LEE. It is not stubbornness on my part in not answering his previous question, but a lack of clarity of what he meant. The biggest problem of having what he called sewage farms in Hong Kong is that on the Island the population live in an area of about 10 or 12 miles long and 4 miles wide, and the amount of fall that you can get in the sewers in that 10-mile length is negligible. To locate a sewage farm at one end or the other of that 10 or 12-mile strip, even if land can be made available by means of reclamation, would be an almost impossible engineering feat because of the lack of fall. On the other hand, theoretically it would be possible to have a series of sewage farms at one or two-mile intervals along the shore of the harbour to eliminate this need for pumping, but this is clearly undesirable aesthetically and also for practical reasons. There are very real problems about dealing with sewage in Hong Kong. We believe that the methods we are using, and the proposals that are now being put into use in several cases, and the fact that we are doing further work of extending submarine outfalls into the centre of the
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increase in the pollution of harbour water, but, of course, there is a strong tidal stream in the harbour which serves to disperse the sewage which enters these waters.
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