THE CHRISTCHURCH ARTESIANS AND THE CITY WATER SUPPLY.

Star (Christchurch), Issue 17349, 14 May 1924, Page 4

THE CHRISTCHURCH ARTESIANS AND THE CITY WATER SUPPLY.

BY

CHAS. CHILTON

(Sector and Professor of Biology, Canterbury College, N.Z.) XXVIII. AX OPEN’ RESERVOIR ON THE PORT HILLS. Another question that gave rise to much argument in the discussions about the water supply proposals in 1907 was that me reservoir, and a brief reference to it is necessary because of its bearing on the proposals made in the present year. In the wnter s article of June 7, 1907, it was urged that as Nature had supplied abundant stores of pure water under the city there was no need to build a reservoir on the Port Hills in which to store •» le ’ svaler was there where the consumers wanted it and all that was necessary was to allow it to flow up the pipes and to give it the necessary pressure for fire prevention and domestic purposes. It was pointed out that it was a question foi‘ the engineers to decide how the pressure was to be obtained, hut that in a place so level as Christchurch the problem ought to be an easy one, and that the pressure could be obtained by means of a water tower, as was already being done at Sydenham, or by pumping directly into the mains, as was done in many towns in other parts of the world. Among the schemes for the extension of the water supply considered by the City Council last year was one, known as “ No. 1 scheme,” in which there was an item ” Reservoir complete to hold 9,000,000 gallons, £52,000,” and another for the purchase of a site at a cost of- £1368. The reservoir was not included in “ No. 2 scheme,” which \yas the one submitted to the citizens at the poll in January last, hut the £1368 was put down for the site “ for future requirements,” and it has been admitted that the site has been already purchased. Whether a reservoir of any kind is needed may be discussed later, but the reservoir proposed in 1907 was to be an open reservoir, and this was strongly objected to by the present writer. In the article quoted he said:— “In an ( open reservoir our artesian water, unequalled in its purity, would be exposed to all the germs that blow • about in the dust storms of which we have so many, and we should soon have growing in the water all sorts of obnoxious plants and animals, and the purity of our water would be lost.” It was added that the writer was not speaking at random, and the proof of this appeared at the first meeting of citizens at which the proposals of the council were explained. At that meeting he produced a bottle of water obtained from the service pipe of a town supplied from an artesian source, but which, through the use of an open reservoir, had become contaminated and when examined was found to contain a small water shrimp, two kinds of water fleas, a small shellfish, a polyzoon known as “ Plumatella,” aquatic worms, insect larvae, rotifers, infusoria, etc. This was evidently an example of a “ pipe-fauna ” and was very similar to the pipe-fauna described by Dr Kraepelin in 1886 from the water pipes supplying the city of Hamburg, in which, however, a water sponge was also present. In that case the city was supplied with unfiltered water drawn from the river Elbe into reservoirs, whence it flowed into mains supplying the inhabitants. An interesting account of the Hamburg case and of similar occurrences elsewhere was published in 1917 in the British Museum Economic Series under the title “ The Biology of Waterworks.” In this the author, Mr R. Kirkpatrick, points out that, while the conditions of existence in the pipes eliminate all green plants, vegetable feeders and air-breathers, they encourage fixed forms requiring a secure foundation (such as the Plumatella and the freshwater sponge) and animals living on diatoms and organic debris, also small carnivorous creatures such as certain worms and Crustacea. The polyzoa and sponges were vastly more abundant in the pipes than in the Elbe, because in the pipes they had a more secure foundation than on the muddy and sandy bottom of the river and a continuous supply of food would be more liable to be within reach in a current passing through a pipe than in the broad channel of the river. The water supply of Hamburg became notorious in 1892, because of an epidemic of cholera which arose from the Elbe being contaminated with cholera germs owing to the proximity of a camp of Russian emigrants and the germs being spread to the inhabitants through the water pipes. In Hamburg a system of sand filtration was introduced in 1894, the whole pipe fauna died of starvation and its remains soon disappeared. The story of the Hamburg pipe fauna was related in 1907 to emphasise the fact that in Christchurch we had pure, naturally filtered water in the artesians and that if proper precautions were taken it need never become contaminated in any way, hut that this was always possible if an open reservoir was used. Naturally, as was pointed out by the Public Health Officer at the lime, many cities have to be supplied from open reservoirs and if the vegetable growth in them is kept down by suitable means any contamination that takes place does not affect the purity of the water to any extent that need be taken into consideration. These and other similar arguments were used in support of the reservoir proposed by the City Council, and so little was the position of Christchurch as regards its source of pure water understood that it was* even argued that other towns, such as , Sydney, Melbourne 'and Dunedin had reservoirs and Christchurch ought to have one also. The loan for the City Council’s proposals was carried at the poll on June 26, . 1907, and the open reservoir was constructed on the Port Hills. But evidently. the discussion had made some impression, for here again the sequel is interesting. About eighteen months later, on the recommendation of the engineer, a ferro-concrete cover was put over the reservoir at an estimated cost of £I6OO.

(The next article will appear on Saturday, May 17, 1924.)