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
Results before Treatment | |||||
---|---|---|---|---|---|
Thames Derived | New River Derived | Hoe Lane Well Derived | Hadley Road Well Derived | Waltham Abbey Well Derived | |
Number of Samples | 8,154 | 1,504 | 249 | 250 | 251 |
Agar Plate Count per ml. 20-24 hrs. at 37°C | 53.9 | 82.8 | 0.1 | 0.4 | 0.2 |
3 days at 22°C | - | - | 14 | 64 | 9 |
Coliform Count Percentage of samples neg. in 100 ml. | 40.37 | 40.69 | 100.0 | 84.00 | 99.20 |
Count per 100 ml. | 12.2 | 14.2 | - | 3.1 | 0.1 |
Escherichia coli Count Percentage of samples neg. in 100 ml. | 54.91 | 60.31 | 100.0 | 86.00 | 100.0 |
Count per 100 ml. | 5.1 | 2.5 | - | 2.2 | - |
Number of Samples | 3,901 | 515 | 253 | 249 | 254 |
Agar Plate Count per ml. 20-24 hrs. at 37°C | 8.4 | 14.7 | 0.1 | 0.1 | 0.8 |
3 days at 22°C | - | - | 8 | 11 | 17 |
Coliform Count Percentage of samples neg. in 100 ml. | 99.51 | 100.0 | 100.0 | 100.0 | 99.61 |
Escherichia coli Count Percentage of samples neg. in 100 ml. | 99.97 | 100.0 | 100.0 | 100.0 | 100.0 |
Chemical Results Expressed in Milligrammes per Litre | |||||||
---|---|---|---|---|---|---|---|
Appearance | Clear and Bright | Ammoniacal Nitrogen | 0.02 | ||||
Colour (Burgess) | Less than 5 | Albuminoid Nitrogen | 0.00 | ||||
Odour/Taste | Nil/Nil | Nitrate Nitrogen | 8.0 | ||||
Turbidity | 0 | Nitrite Nitrogen | 0.00 | ||||
Conductivity | 600 | Oxygen Absorbed | 0.30 | ||||
Total Solids | 445 | Fluoride less than | 0.2 | ||||
pH | 7.2 | Silica | 15 | ||||
Free CO2 | 30 | Iron less than | 0.02 | ||||
Alkalinity (CaCo3) | 210 | Other metals: Copper/Zinc/Lead | absent | ||||
Carbonate Hardness | 210 | Phosphate | 0.11 | ||||
Non-Carbonate Hardness | 120 | Residual Chlorine | Nil | ||||
Total Hardness | 330 | Temperature (°C) | 8.5 | ||||
No. of Colonies developing on Agar | |||||||
0 per ml. | 1 per ml. | 4 per ml. | |||||
Presumptive Coli-Aerogenes.. | — ml. | 100 ml. | 0 per 100 ml. | ||||
E. Coli | — ml. | 100 ml. | 0 per 100 ml. | ||||
CI. Welchii | — ml. | — ml. |