London's Pulse: Medical Officer of Health reports 1848-1972
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Hints from the Health Department. Leaflet from the archive of the Society of Medical Officers of Health. Credit: Wellcome Collection, London
Sutton 1967
[Report of the Medical Officer of Health for Sutton]
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(ii) The number of samples collected and the bacteriological and chemical analyses of the supply from the above sources after treatment are shown as follows :-
| Bacteriological Results - Yearly Averages, 1967. After Treatment | ||||
|---|---|---|---|---|
| Number of Samples | Agar plate count per ml. | Coliform count | E. coli count | |
| 20-24 hours at 37°C. | 3 days at 22°C. | Per cent samples negative in 100 ml. | Per cent samples negative in 100 ml. | |
| 1,887 | 8.8 | 99.52 | 99.95 | |
Average Results of the Chemical Examination of Water, 1967. Milligrammes per litre (unless otherwise stated)
| No. of Samples | 156 | Chloride as C1 | 30 |
| Ammoniacal Nitrogen | 0.021 | Phosphate as PO4 | 1.9 |
| Albuminoid Nitrogen | 0.088 | Silicate as Si02 | 9 |
| Nitrate Nitrogen | 4.2 | Sulphate as S04 | 64 |
| Oxygen abs. from KMnO4 4 hrs at 270c. | 1.12 | Natural Fluoride as F | 0.30 |
| Hardness (total) CaCO3 | 272 | Surface-active material as Manoxol 0T | 0.01 |
| Hardness (non-carbonate) CaC03 | 69 | Turbidity units | 0.1 |
| Magnesium as Mg | 5 | Colour (Burgess units) | 12 |
| Sodium as Na | 22.6 | pH value | 7.9 |
| Potasium as K | 5.1 | Electrical Conductivity (micromhos) | 580 |
No fluoride was added, and where the fluoride content is indicated it
represents the naturally occurring fluoride in the water.
(c) The supply, being hard in character, is not liable to be plumbosolvent.
(d) All new and repaired mains are disinfected with chlorine; after
a predetermined period of contact the pipes are flushed out and
refilled; samples of water are then collected from these
treated mains; and the mains are returned to service only after
results are found to be satisfactory. The quality control from
these laboratories is carried out by means of daily sampling
from sources of supply, through the treatment works or well
stations, from the distribution system, and through to the
consumer. Any sign of contamination or any other abnormality
is immediately investigated.
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