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
Enfield 1970
[Report of the Medical Officer of Health for Enfield]
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ENVIRONMENTAL HEALTH*
Table 30 Water Supply Metropolitan Water Board Average Bacteriological Results
| Results before Treatment | |||||
|---|---|---|---|---|---|
| Thames Derived | New River Derived | Hoe Lane Well Derived | Hadley Road Well Derived | Waltham Abbey Well Derived | |
| Number of Samples | 8,259 | 1,510 | 246 | 242 | 247 |
| Agar Plate Count per ml. 20-24 hrs at 37°C | 31.9 | 46.1 | 0.1 | 0.1 | 0.0 |
| 3 days at 22°C. | — | — | 17 | 9 | 30 |
| Coliform Count Percentage of samples neg. in 100 ml. | 37.91 | 42.91 | 98.37 | 80.99 | 99.60 |
| Count per 100 ml. | 17.3 | 8.1 | 0.1 | 0.5 | — |
| Escherichia coli Count Percentage of samples neg. in 100 ml. | 53.58 | 60.79 | 100.0 | 84.30 | 100.0 |
| Count per 100 ml | 4.7 | 2.2 | — | 0.3 | — |
| Results after Treatment | |||||
| Number of Samples | 3,710 | 516 | 254 | 248 | 253 |
| Agar Plate Count per ml. 20.24 hrs. at 37°C | 8.0 | 10.9 | 0.3 | 0.1 | 0.2 |
| 3 days at 22°C. | — | — | 7 | 33 | 38 |
| Coliform Count Percentage of samples neg. in 100 ml. | 99.92 | 100.0 | 100.0 | 100.0 | 100.0 |
| Escherichia coli Count Percentage of samples neg. in 100 ml. | 99.97 | 100.0 | 100.0 | 100.0 | 100.0 |
Table 31
Water Supply
Lee Valley Water Company Representative Sample
| Chemical Results Expressed in Milligrams per Litre | ||||||
|---|---|---|---|---|---|---|
| Appearance | Clear and Bright | Ammoniacal Nitrogen | 0.00 | |||
| Colour (Burgess) | Less than 5 | Albuminoid Nitrogen | 0.00 | |||
| Odour/Taste | Nil | Nitrate Nitrogen | 6.3 | |||
| Turbidity | 0 | Nitrite Nitrogen | 0.00 | |||
| Conductivity | 560 | Oxygen Absorbed | 0.00 | |||
| Total Solids | 370 | Fluoride less than | 0.2 | |||
| pH | 7.2 | Silica | 9 | |||
| Free CO2 | 49 | Iron | 0.02 | |||
| Alkalinity (CaCO3) | 225 | Other metals: Copper/Zinc/Lead | Absent | |||
| Carbonate Hardness | 225 | Phosphate | 0.15 | |||
| Non.Carbonate Hardness | 100 | Residual Chlorine | nil | |||
| Total Hardness | 325 | Temperature (°C.) | 11.0 | |||
| Bacteriological Examination | ||||||
| No. of Colonies Developing on Agar | 1 day at 37°C. | 2 days at 37°C. | 3 days at 20°C. | |||
| 0 per ml. | 0 per ml. | 12 per ml. | ||||
| Present in | Absent from | Probable No. | ||||
| Presumptive Coli.Aerogenes | — ml. | 100 ml. | 0 per 100 ml. | |||
| E. Coli | — ml. | 100 ml. | 0 per 100 ml. | |||
| CI. Welchii | — ml. | — ml. | ||||