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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TABLE 32
WATER SUPPLY Metropolitan Water Board Average Bacteriological Results
Results before Treatment | |||||
---|---|---|---|---|---|
Thames Derived North of River | New River Derived | Hoe Lane Well Derived | Hadley Road Well Derived | Waltham Abbey Well Derived | |
Number of Samples | _ | _ | 194 | 247 | 245 |
Agar Plate Count per ml. 20-24 hrs. at 37 °C | _ | 6.3 | 0.4 | 0.1 | |
3 days at 22 °C | — | — | 16 | 44 | 6 |
Coliform Count Percentage of samples in neg. 100 ml | _- | _ | 99.48 | 85.43 | 99.59 |
Count per 100 ml Escherichia coli Count | — | — | - | 0.6 | - |
Percentage of samples in neg. 100 ml | — | — | 99.48 | 88.26 | 100.0 |
Count per 100 ml | — | — | — | 0.3 | — |
Results after Treatment | |||||
Number of Samples Agar Plate Count per ml. | 1,720 | 514 | 199 | 252 | 252 |
20-24 hours at 37°C. | 12.1 | 11.9 | 0.1 | 2.0 | 0.0 |
3 days at 22°C Coliform Count | — | — | 24 | 19 | 16 |
Percentage of samples in neg. 100ml Escherichia coli Count | 99.94 | 100.0 | 100.0 | 100.0 | 100.0 |
Percentageofsamplesinneg. 100ml | 99.94 | 100.0 | 100.0 | 100.0 | 100.0 |
TABLE 33
WATER SUPPLY Lee Valley Water Company Representative Sample
Chemical Results Expressed in Milligrams per Litre | |||||
Appearance | Clear and Bright | Ammoniacal Nitrogen 0.01 | |||
Colour (Burgess) | Less than 5 | Albuminoid Nitrogen 0.01 | |||
Odour/Taste | Nil/Nil | Nitrate Nitrogen 7.0 | |||
Turbidity | 0 | Nitrite Nitrogen 0.00 | |||
Conductivity | 590 | Oxygen Absorbed 0.02 | |||
Total Solids | 405 | Fluoride less than 0.2 | |||
PH | 7.2 | Silica 12 | |||
Free CO2 | 31 | Iron less than 0.02 | |||
Alkalinity (CaCO2) | 220 | Other Metals: Copper/Zinc/Lead Absent | |||
Carbonate Hardness | 220 | Phosphate 0.16 | |||
Non-Carbonate Hardness . | 90 | Residual Chlorine Nil | |||
Total Hardness | 310 | Temperature (°C.) 2 | |||
Bacteriological Examination | |||||
No. of Colonies developing on Agar | 1 day at 37°C. 0 per ml. | 2 days at 37°C. 1 per ml. | 3 days at 20°C. 5 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. |