Hints from the Health Department. Leaflet from the archive of the Society of Medical Officers of Health. Credit: Wellcome Collection, London
[Report of the Medical Officer of Health for Enfield]
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ENVIRONMENTAL HEALTH
(27) Water supply - Metropolitan Water Board: average bacteriological results
Results before treatment | ||||||
---|---|---|---|---|---|---|
New River Derived | Copper -mills Derived | Thames Derived | Hoe Lane Well Derived | Hadley Road Well Derived | Waltham Abbey Well Derived | |
Number of samples | 1,506 | 994 | 8,087 | 251 | 293 | 250 |
Agar Plate Count per ml. 20-24 hrs. at 37°C ... | 58.8 | 82.2 | 42.3 | 0.3 | 0.6 | 0.1 |
3 days at 22°C | — | — | — | 11 | 38 | 12 |
Coliform Count Percentage of samples neg in 100 ml. | 55.91 | 41.65 | 41.94 | 98.41 | 68.60 | 99.60 |
Count per 100 ml. | 4.2 | 17.2 | 10.2 | — | 2.2 | — |
Escherichia coli Count Percentage of samples neg in 100 ml. | 70.25 | 61.89 | 56.76 | 99.20 | 72.01 | 99.60 |
Count per 100 ml. | 1.1 | 2.6 | 4.0 | — | 1.4 | — |
Results after treatment | ||||||
Number of samples | 510 | 255 | 3,891 | 254 | 252 | 251 |
Agar Plate Count per ml. 20-24 hrs. at 37°C ... 3 days at 22°C | 20.1 | 9.4 | 10.0 | 0.4 15 | 0.2 8 | 0.1 9 |
Coliform Count Percentage of samples neg in 100 ml. | 100.0 | 100.0 | 99.85 | 100.0 | 100.0 | 100.0 |
Escherichia coli Count Percentage of samples neg in 100 ml. | 100.0 | 100.0 | 99.97 | 100.0 | 100.0 | 100.0 |