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 Chigwell]
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Lee Bridge | Copper-mills | Chingford Mill | Ferry Lane | Waltham Abbey | |
---|---|---|---|---|---|
Surface-active material as Manoxol OT | 0.03 | 0.03 | - | - | - |
Turbidity units | 0.1 | 0.1 | 0.1 | 0.1 | 0.4 |
Colour (Burgess units) | 12 | 10 | 6 | 2 | 7 |
pH value | 8.1 | 8c2 | 7.5 | 7.7 | 7.5 |
Electrical Conductivity (micromhos) | 660 | 650 | 530 | 850 | 550 |
(b) Results of Bacteriological Examination:- | |||||
BEFORE TREATMENT- | |||||
No. of samples | 2,675 | 308 | 250 | 77 | 249 |
Agar plate count per ml,:- | |||||
20-24 hours at 37°C | 203.5 | 130.8 | 0.4 | 0.3 | 0.1 |
3 days at 22°C | - | - | 8 | - | 9 |
Coliform count:- | |||||
Per cent, samples negative in 100 ml | 40.67 | 45.13 | 100.0 | 98.70 | 99.60 |
Count per 100 ml | 9.3 | 14.7 | - | - | - |
Escherichia coli count:- | |||||
Per cent samples negative in 100 ml | 60.34 | 68.51 | 100.0 | 100.0 | 100.0 |
Count per 100 ml | 2.3 | 1.6 | - | - | - |
AFTER TREATMENT - | |||||
No. of samples | 495 | 127 | 250 | *79 | 253 |
Agar plate count pgr ml.:- | |||||
20-24 hours at 37°C | 52.0 | 43.5 | 0.3 | 7.1 | 0.2 |
3 days at 22°C | - | - | 4 | - | 6 |
Coliform count:- | |||||
Per cent, samples negative in 100 ml | 99.60 | 100.0 | 100.0 | 100.0 | 99.60 |
E. c oil count:- | |||||
Per cent. samples negative in 100 ml | 99.80 | 100.0 | 100.0 | l00.0 | 100.0 |
* Mixed with filtered River Lee - derived water before chlorination." /2. |