[Report 1931] / Medical Officer of Health, Perth City.

  • Perth (Scotland). City Council.
Date:
1931
Catalogue details

Licence: Attribution 4.0 International (CC BY 4.0)

Credit: [Report 1931] / Medical Officer of Health, Perth City. Source: Wellcome Collection.

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    I would consider, therefore, that good technique had been employed and sound judgement had been manifested by those responsible for the process of chlorination. 4. Distribution Area. The results obtained in examining the water as distributed corroborate the opinion expressed above concerning its examination at once after chlorination. As distributed, the water is of a high standard of purity, as is shown by its low bacteria] content, and by the fact that only on one occasion was the colon bacillus demon- strated in less quantity than 100 c.c., while on four occasions, April 7, May 5, June 2 and June 29, that micro-organism was not demonstrable even in 100 c.c. It is worthy of note that the exceptional occasion when colon bacilli were recovered from 10 c c. of the water was on November 3. The findings, therefore, show that although the raw river water has too rich a bacterial flora to constitute a safe source of water for domestic supplv, its subsequent treatment by filtration and chlorina- tion renders it safe and satisfactory in that regard. I would lay special stress on the fact that the degree of chlorina- tion, as shown by my examinations, is adequate and, what is equally important, is well controlled and not excessive. 7/1/32. (Signed) WILLIAM J. TULLOCH. The samples have, with one exception, been taken on the first Tuesday in each month. They are thus in a sense “ random ” samples, and include samples taken in all states of the river between “summer level ” and spate. The average amount of chlorine used during 1931 was one part in 2 million or 24% less than during 1930.
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