*
6
7
REQUIREMENTS FOR INTERMITTENT SUPPLY.
24. It is a matter of considerable regret that it has been found necessary to introduce, at any period of the year, the intermittent system of water supply, and I thoroughly approve the course the Government has adopted in postponing to the last moment the introduction of such a system.
25. From statements which have appeared in the public press of the Colony, it appears that considerable misunderstanding exists on the subject of the desirability of adopting the intermittent system of supply, either temporarily or occasionally. I therefore propose to point out the dangers to health and general inconvenience which are the result of this vicious system of water supply, now universally condemned by every sanitarian. But before proceed- ing to do so, I will describe the appliances which must be provided in every tenement, in order to carry out an intermittent supply with such a degree of efficiency as a radically bad system can attain.
26. Each house must be provided with a cistern, capable of containing at least a day's supply of water. A pipe must be taken from the main to this cistern, and there must be no tap or other outlet connected with it. The orifice at the cistern must be provided with a ball-valve, which shuts off the water when the cistern is full. All taps must be connected to the cistern alone. Such are the appliances which are still in use in portions of London and elsewhere, wherever the intermittent supply is in force.
27. Now the cost of providing and fixing a proper cistern and ball-valve, with the necessary alterations to pipes and fittings, would not cost less than £3 in England at least; say $30 in Hong Kong, and possibly in many cases considerably more.
28. The city of Victoria is hilly; the network of mains has not been designed with a view to an intermittent supply. Very considerable alterations must be made in order to distribute the water uniformly, so that houses at a low level do not get an excessive supply, whilst those higher up get little or
none.
In many instances I believe that it would be necessary to provide new branch-mains to supply groups of tenements. Indeed this would be necessary throughout, if the existing pipes were to be kept permanently charged ready for fire. Clearly, therefore, the introduction of a complete intermittent system would be costly.
29. Would the reduction in consumption be appreciable and commensurate with the cost of such a retrograde step as the introduction of the intermittent system? According to English experience the consumption of water is actually greater under the intermittent system than with a reasonably well-managed constant supply. There is actually more waste. People leave their taps open or allow them to become leaky, and when the water is turned on a great proportion runs to waste. Ball-valves continually get out of order, and allow
the cistern to overflow. Quite as much vigilance and supervision is required under the intermittent as under the constant system if waste is to be kept within bounds.
30. The legitimate consumption of water would be the same, whether the water be turned on for one hour or twenty-four. All that the intermittent system can effect is to check legitimate consumption by restricting the supply; and unless the whole network of mains were modified it would be impossible to do so with any approach to uniformity or fairness. One house would get a full supply whilst another would get little or none.
EVILS OF INTERMITTENT SUPPLY.
31. The intermittent system, even in its most perfect form, has a radical defect. The water must be stored in or near the dwelling, and is, therefore, liable to contamination of the most dangerous nature. Those who made the recent house-to-house examination, will be able to appreciate the condition of the places in which cisterns would be placed, and the condition in which they would be kept.
32. In addition to this defect, which is inseparable from the intermittent system, it presents, as carried out in Hong Kong, the following disadvantages :-
left
(a) The entrance of foul air, foul liquids, and possibly disease- germs into the public water-mains.
(b) The growth of fungoids and corrosion in the pipes.
(c) The undue wear and tear of the distribution system.
(d) The difficulty of equitable distribution of water throughout
the Waterworks area.
(e) The waste of water.
(/) The failure to provide efficient fire service.
33. As regards (a). It must be recollected that, with an intermittent system
of supply, after the water is shut off from the mains, the taps in the lower parts of the district remain running till the mains are emptied, and during the gradual drawing off of the water, air enters into the mains to replace the portions previously occupied by the water. This air enters through several open taps, situated in various positions on private premises, which have been open to obtain water as long as possible after it has been shut off from the main, and as soon as possible on its being turned on again. Air is, therefore, actually drawn from the interior of houses and back-yards. This air is more or less absorbed by the water, and in the event of its being seriously polluted may be the means of conveying disease. When the mains are emptied the balls of the hydrants fall and there is a free communication between the main and the box through which, not air alone, but actual dirt can gain access to the pipes. That taps are left open, to a very considerable extent, is no surmise,
638
No comments yet.
Private notes are available after approval.