THE B. COLI SCARE.

Southland Times, Issue 19502, 17 March 1925, Page 6

THE B. COLI SCARE.

There is a danger that the opponents of the Dunsdale scheme will make too much of the arrival of the Bacillus Coli on the scene. Mr John Miller has uttered a fearful warning to the ratepayer about the dangers of a water supply which shows, as the bacteriologist states, a few B. Coli under a microscopical examination. The B. (Coli is to be found in most water supplies, and it wall not be entirely eliminated by filtration. The first sample taken from the Dunsdale showed a few’ B. Coli. In this connection it is well to quote Savage, who is recognised as an authority on this subject:—•

In upland surface waters the presence of B. Coli in 40, 10, or even in 2 or 1 c.c. means contamination, but not necessarily a contamination which it is essential to prevent: If B. Coli are present in qumbers greater than say, 500 per litre (or even in that amount), such water is suspicious, and further investigation is desirable. In filtered samples the number of B. Coli is, as a rule, considerably reduced.

It will be noticed that Savage, unlike Mr Miller, does not consider water suspicious because the presence of B. Coli in 1 c.c. is detected, and we must infer, too, that even in filtered water B. Coli will be found. It is announced that the second sample of Dunsdale water disclosed no B. Coli at all, but the point to be borne in mind is that in the 20 colonies on the Agar plates, a microscopical examination detected “a few B. Coli.” This probably is the explanation of the things that puzzled Mr Miller—Dr Johnston’s readiness to say that

the sample of the water from the Dunsdale indicates that the water is particularly free from contamination, either by humans or animals.

The B. Coli scare is trumpery, and its value may be discovered if a sample of the water now being supplied in Invercargill is examined. Taking into account the fact that the water at present is stored for a time in open reservoirs to which dust from the streets and refuse have access, it will not be at all surprising if the B. Coli, which has caused Mr Miller so much concern, is not discovered in a sample taken from the mains. In other words, so far as the B. Coli is concerned, the water now being used by the people of Invercargill is no better than that taken from the Dunsdale, and after the years of experience with the pumped water, that surely would be an ample clearance for Dunsdale. Mr Miller, we think, has not gone deep enough into the subject.