TOWN WATER SUPPLY

Southland Times, Issue 19501, 16 March 1925, Page 7

TOWN WATER SUPPLY

THE DUNSDALE SCHEME ANALYTICAL TESTS MADE “WATER OF THE VERY BEST QUALITY.” The Towns Clerk (Mn-F. Burwell) has received from the analysts the following favourable chemical analysis of water, from the Dunsdale stream: — I have analysed the sample of water ex Dunsdale, which you sent me on 28/2/25. The water is perfectly clear, and free from odour or taint. It is evident that the water flows over rocks of a hard nature, and so the mineral matter in solution is low. This is in its favour for use in boilers and it also means a great saving in the consumption of soap for washing. The organic matter present is from a vegetable source, and the amount is small.

There is an absence of nitrogen from animal matter. The water is therefore of the very best quality, and can be thoroughly recommended from a chemical or health point of view and leaves the only question at issue, viz., quantity and continuity of supply. ANALYSIS. grains per gallon. Sulphate of Lime 0.093 Carbonate of Lime .. .. 2.685 Carbonate of Magnesia .. 1.366 Chloride of Sodium (salt) 0.104 Soluble Organic Matter .. 0.082 4.330 Matter in suspension .. .. 1.738 Total Solids 6.068 (Sgd.) GEO. D. MACINDOE, M.A.C.1., Invercargill Borough Analyst. ANALYSIS OF WATER FROM No. 4 BORE. grains per gallon. Sulphate of Lime ~ 0.835 Magnesium Chloride .. .. 0.603 Sodium Chloride (salt) .. 7.300 Carbonate of Lime 2.432 Organic Matter 0.173 Clay 0.269 Oxide of Iron 0.455 Total solids 12.067 G. D. MACINDOE, M.A.C.1., October 23, 1923. The bacteriologist has not completed examination of the second sample of Dunsdale water, which he wished to make in view of the exceptional purity of the first sample tested, 3/3/25. WATER FROM DUNSDALE FOR BACTERIOLOGICAL EXAM. 1 c.c Agar plate after 48 hours incubation at 37 degress c., 20 colonies. 1 c.c. Gelatine plates after 72 hours at roof temperature, 2080 colonies. 5 c.c. Bile Salt hactose Agar:—No growth. Bile Salt hactose broth, growth in 25 c.c’s. Bile Salt hactose broth, growth in 10 c.c’s. Bile Salt hactose broth, growth in 5 c.c’s. Bile Salt hactose broth, no growth in 1 c.c. Microscopical examination showed a few B. Coli. L.S. The result of the above bacteriological examination of the sample of water from Dunsdale indicates that the water is particularly free from contamination either by humans or animals. I would suggest that further samples be taken under varying climatic conditions. A. OWEN JOHNSTON M.8.Ch.8. THE BACTERIOLOGIST’S REPORT. (To the Editor). Sir, —Some time ago I advised that a bacterial examination as well as a chemical analysis should be obtained of the water from the Dunsdale. 1 beg permission to say something about the results of those examinations. I shall deal first with the chemical analysis. We have been told that the water at the Dunsdale is a soft water, and that a great saving in soap and labour would result in its uses. Most people know that one of the principal things which causes hardness of water is carbonate of lime, and of this you have in the Dunsdale water 2.685 grains to the gallon and in the water from the No. 4 Bore you have 2.432 grains to the gallon. Of the other substances which cause hardness you have sulphate of lime, Dunsdale 0.093 grs., No. 4 Bore 0.835 grs. to the gallon; carbonate of magnesia, Dunsdale 1.366 grains, No. 4 Bore nil; chloride of magnesia, Dunsdale nil, No. 4 Bore 0.603 grains to the gallon. There is more lime and magnesia, substances which harden water, in the Dunsdale water than in that from the No. 4 Bore, the amount being respectively 4.144 and 3.870 grains to the gallon. Of chloride of sodium or common salt, Dunsdale’s water contains 0.1Q4 and No. 4 Bore 7.300 grains to the gallon. Salt exists in variable amounts in every soil and hence in every water, it abounds in the tissues and fluids of man, animals and plants, its value as a condiment is well known, animals as well as ourselves require it. Salt is a stimulant, a tonic and an antiseptic, it is essential for the maintenance of health. We ought to be thankful that our present water supply contains 7.300 grains to the gallon. Matter in suspension (clay) Dunsdale water contains 1.738 grains to the gallon, that from No. 4 Bore contains 0.269 grains to the gallon. Next we come to oxide or iron. The Dunsdale water contains none of this, while the water from No. 4 Bore contains 0.455 or less than half a grain to the gallon. Much is being made of the presence of this iron in the Tower water, causing encrustation of pipes, tubes and boilers, but that is a matter of L.S.D. Can anyone say that the water from the Tower has ever done the tubes of the human body any harm ? When one studies the contents of the water from the Tower, viz., lime, magnesia, salt and iron, one can only come to the conclusion that it must have been, and is, playing an important part in building up strong and healthy children. The most important question relating to the quality of a water is whether it is dangerous to the health, hence the necessity of having a thorough bacteriological examination. So far as I am aware this is the first time that such an examination of the Dunsdale water has been made, the result of which I had handed to me on Saturday last. It conveys little to the general public except that Mr Shearer, the Bacteriologist, was able to grow on the different substances bacteria from the sample of waters submitted to him. All surface waters contain bacteria, many of which are probably quite harmless, and these can be got rid of by filtration. A most important point, however, in his report, is that microscopical examination showed a few bacillus coli. The presence of these bacilli in the water proves beyond all doubt that the water is contaminated. The bacillus coli is a normal inhabitant of the intestines of man, cattle, swine, dogs and other animals. They are an easily recognised species characteristic of sewage and other wastes of animal origin. These bacillus coli can also be got rid of by filtration and it is highly desirable that a purification plant should operate in such a manner that bacillus coli are rarely found in the purified water. In the face of these facts I fail to understand why Dr. Owen Johnstone states that the water is particularly free from contamination either by humans or animals, but he takes the precaution of suggesting that further samples be taken under varying climatic conditions. I agree with that, and consider that the people of Invercargill should insist on every precaution being taken to ensure a pure water supply. As I have already stated, these organisms can be got rid of by fitfcny- j

tion, but the Engineer has stated that there is no need to filter the Dunsdale water, and has made no provision for doing so. I have always considered it necessary, and in view of the result of the bacteriological examination, I am more convinced than ever. —I am, etc., JOHN MILLER, M.R.C.V.S., QUALITY AND QUANTITY. To the Editor. Sir, —As a ratepayer and one well acquainted with the Dunsdale stream, might 1 add my quota to the discussion that has engaged the interest of the public for some time. From about 1900 to about seven years ago I resided at Hedgehope and during the whole of that time I was on the Dunsdale shooting or fishing two or three times a month and have countless times traversed the stream from where it joins the Hedgehope to its source in the Hokonui Hills. Under a week ago I saw the water flowing through two six-inch pipes situated at the weir constructed by or at the instance of the Borough Engineer and can say with positive certainty that about 14 years ago and before the present lesee of the Borough Council took up his lease I have seen the stream so low that it would not fill a sixinch pipe, and that was at the place where the weir is constructed on a rocky bed. So low indeed was the stream that the fish died through lack of fresh water. If the water had been percolating through the gravel the fish would have lived. So the dry spell must have continued for a long time. If there was no doubt about the quantity of the water, would the authorities be making such exhaustive measurements as are being taken at present? Then, with regard to the quality. When I was there a week ago there was a fresh on in the stream and the water was far from wholesome; in fact, the tea made on the spot by the Corporation employees was hardly drinkable, as several can testify. Every time there is a slight fresh in a stream arising in a bush-clad catchment area, and the catchment area of the Dunsdale is entirely bush-clad, the water comes down bearing leaves, more or less decomposed, of fuschia, broadleaf and of countless other varieties of trees and undergrowth which leaves impart to the water a blackish tinge. The thousands of acres of bush draining into the upper reaches of the Dunsdale shed annually thousands of tons of leaves, large volumes of which would find a resting place at the bottom of the dam and would, I consider, in time fill the same up and in the meantime pollute the water lying there.

Why is the Makarewa dark and discoloured? It has its origin in the same bushclad ranges, and even when at its lowest the water is much darker than, say, the Oreti.

His Worship the Mayor condemns the Oreti scheme and one of his reasons is on account of the sewerage that it is or might be deposited therein by the townships of Dipton and Lumsden, but that is easily stopped and, if necessary, the deposit of sewerage in this river could be prohibited by law if the same is not so at present. The Dunsdale is at best a temporary scheme and in the course of time the supply of water therefrom would have to be augmented to cope with the additional population which will come, so why not go now to the Oreti?

The dam at that river could be made some distance from its bed and the water could be cleansed by percolating or filtering through the gravel. Indeed, the water here is always wholesome on account of the miles of shingly bed it ripples over, rather different from the Dunsdale scheme, in which the water flows from a hole in the bush through pipes to the consumer. Previous correspondents have cited the higher altitude of the Oreti, the fact that riparian rights would not be disturbed and the fact that the pines could be laid on railway land, so I will not take up more of your valuable space by commending what I consider is the better scheme and condemning the useless one. I am, etc., W. PEARSE. THE SOURCE OF THE DUNSDALE. To the Editor. Sir, —An important matter for consideration in regard to the proposed Dunsdale water supply scheme is the question of the full control of the main source from which the water has to be secured. The only stream actually within the full control of the Borough Council is apparently a very small tributary of the real Dunsdale stream. Portion of the Dunsdale stream does actually flow through the Corporation Reserve, but there are headwaters beyond the Reserve—for about five miles—which is the principal territory that provides the water. This territory is quite outside the jurisdiction of the Corporation. It is, in fact, a large Native Reserve, all bush-clad, and is not yet utilised as a sawmilling area, but is quite likely eventually to be opened up for sawmilling. This circumstances presents a difficulty which must be overcome before the Dunsdale proposal can be deemed in any degree safe, as regards a pure water supply. Such a position, while regrettable, is, none the less, self-evident, and it would not be sound business, much less commonsense, to allow the Dunsdale proposals to go through until this matter has been placed on a thoroughly sound and satisfactory basis. I am, etc., WILLIAM MAXWELL.