TOWN WATER SUPPLY

Southland Times, Issue 19502, 17 March 1925, Page 7

TOWN WATER SUPPLY

PUMPING v. GRAVITATION THE PRESENT CONTROVERSY VIEWS OF MEDICAL MEN. The controversy regarding the Dunsdale water supply scheme, which is to be placed before the ratepayers to-morrow for their sanction to raise the necessary money to carry out the project, shows no signs of diminishing, and the views expressed by the various correspondents in the Southland Times yesterday morning is said to have afforded the supporters and opponents of the scheme some food for thought. With a view to ascertaining the opinion held by members of the medical profession resident in Invercargill, a representative of the Southland Times yesterday waited upon a number of them and solicited their views on the question from a medical point of view, and also to seek their comments on the matters raised in the letter written by Mr John Miller, M.R.C.V.S., who among other things stressed the view that filtration of the water would be necessary owing to the fact that some bacillus coli had been detected in the samples of the Dunsdale water which had been bacteriologically examined. Mr Miller’s view that this was an essential factor was not agreed to by several of the doctors who were approached, and who were able to briefly discuss the question. The opinion which they held, however, was that further samples of the water should be tested under varying conditions before the necessity of filtration could be finally disposed of. The fact that a small percentage of bacillus coli had been found did not, they averred, constitute a danger of infection because indications of this particular body were to be found in water supplies which had been filtered for the purpose of eliminating these foreign matters.

The absence of any definite information from the bacteriologist as to the extent to which bacillus coli was present in the samples of water examined was commented upon by some practitioners, who, however, were agreed in their opinion that the analysis was a very satisfactory one from a health point of view. Another point on which there was a general agreement among the medical men interviewed was in regard to the present source of supply, which they stated was quite good and could not be excelled in many other parts of the Dominion. Whether bacillus coli was present or not in that supply, they were not prepared to express any definite opinion, but in proof of their remarks that Invercargill could feel proud of the present supply they mentioned that the almost entire absence of typhoid fever in the town during the last decade was one of the most stringent tests as to the efficacy of the water supply for any community. QUESTION OF FILTRATION. “I do not think that any local practitioner has any decided opinion on the question,” was the remark made by one doctor, “and what is more none of us wish to be drawn into the discussion, which, after all, is one for the health authorities alone to decide as to the purity of the supply. To my mind the main question is what quantity of bacillus coli is permissible in drinking water and, furthermore, what percentage would render it necessary for the water to be filtered. Those questions can, however, only be answered by a competent bacteriologist, but from a cursory examination of the analysis made of the Dunsdale w’ater published to-day I would consider that there is hardly sufficient bacillus coli present to render filtration absolutely essential.”

“Without going into the pros and cons of the matter,” said another medical man, “all I can say is that practically all surface waters are contaminated to a greater or a lesser extent and whether the Dunsdale supply would be dangerous or not on that account would depend on the amount of bacillus coli present in the water. Filtration does not by any means eliminate bacteria from a water supply and authorities are more .or less agreed that water containing 100 c.c. is quite good for drinking purposes without any undue risk of infection.” FREE FROM CONTAMINATION. Another member of the medical profession stated that so far as the bacteriological examination was concerned he was fully in agreement with Dr A. O. Johnston, when he stated that it w’as particularly free from contamination, human or otherwise. It was understood, of course, that no outside supply of water could be entirely free from contamination, but generally speaking ordinary water was not a good pabulum for the growth of germs. Pathogenic, or disease germs, did not tend to live in water, their natural habitat being in organic matter at body temperature. This was illustrated by the fact that in all bacteriological examinations it was necessary in order to promote the growth of germ colonies, to use a temperature approaching as nearly as possible that of the body. In commenting upon Dr Johnston’s statement, Mr J. Miller had made reference to the fact that the analysis had disclosed the presence of a few bacillus coli. This, stated the doctor, was a negligible finding so far as a healthy water supply was concerned, as millions of these bacilli were to be found in the. intestines of the ordinary healthy individual. It was only when the individual’s health was below normal that he was open to contract disease, while there were also much more virulent sources of contamination than the Dunsdale supply was likely to be. Tins was particularly so in the case of the septic tank in the vicinity of Pleasure Bay, for while household septic systems had proved to be an unqualified success the same could not be said of larger systems.

Referring to the chemical analysis the doctor stated that while the present water supply contained a far greater quantity of salt than the Dunsdale, this might not be altogether in its favour. The body could only absorb a certain amount of salt and there was more than sufficient in the Dunsdale water to fulfil its requirements. All surplus salt was excreted and water, in which the percentage of salt was particularly high, placed undue work on the excretive organs.

IMPORTANCE OF ADEQUATE SUPPLY. “To my mind,” said the doctor, “the most important factor to be taken into consideration is that of providing an adequate supply of water for the town’s requirements, for in order to have a healthy community you must have an ample supply of water. The Dunsdale promises to give us this and at the same time to give us a supply particularly free from contamination. My experience of outside water supplies, even in the warmer climates, has been that they have been comparatively free from water-borne disease. Nevertheless I believe it essential that there should be an artificial system of filtration as it would minimise the risks of contamination and free the water from all organic matter.” SMALL QUANTITY OF BACTERIA.

“The question that needs to be answered is-—does the presence of bacillus coli in the amounts that the examination showed render the water unfit for human consumption?” said another local doctor when approached by a Times reporter yesterday in reference to the points raised by Mr John Miller.

“I would not make a definite statement,” he continued, “as the matter is. really one in which the officers of the Department of Health specialise in. The bacteriological examination report gives nothing definite as it states ‘a few’ bacillus coli were found. However, Dr O. Johnston has stated that the water is particularly free from contamination and this is a good recommendation. Filtering would probably get over the difficulty, as if the water was properly filtered it would reach the consumer absolutely free from contamination.

“Again, when the sample of the water was taken the water may have been contaminated for the time being by stock excreta, as I take it that at the present time stock is still allowed to run on the river

areas. In regard to bacteria I will quote authorities—Koch says he would suggest that 100 bacteria per cubic centimeter be the maximum for properly filtered water. Mace proposes that up to 50 per cubic cent, for pure water, and 50 to 500 per cubic cent, for good water be taken as a standard. However, these figures are prefaced by a statement that it is not the quantity of bacteria but the species that matters. For instance, the presence of one typhoid or cholera germ would be sufficient to condemn a whole reservoir. I think,” he said in conclusion, “that the quantity of bacillus coli is very low, otherwise the water would not have received a favourable report,”