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 Chislehurst]
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Before Treatment | Source of Supply | ||||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|
River Thames | Darenth Well | Eynsford No. 1 | Eynsford No. 2 | Horton Kirby No. 1 | Horton Kirby No. 2 | North Orpington No. 1 | North Orpington No. 2 | Short-lands No. 1 | Short-lands No. 2 | Short-lands No. 3 | Wilmington | ||
Southern Group | Bexley Well | ||||||||||||
Number of Samples | - | 251 | 251 | 235 | 122 | 177 | 196 | 159 | 141 | 44 | 79 | 241 | 197 |
Agar plate count per ml. 20-24 hours at 37°C. | - | 2.9 | - | 1.7 | 0.5 | - | - | 2.6 | 1.1 | - | - | 0.1 | 0.2 |
3 days at 22°C. | — | 32 | 10 | 37 | 15 | 79 | 5 | 46 | 57 | 13 | 1 | 3 | 51 |
Coliform count Per cent samples negative in 100 ml | - | 99.60 | 99.20 | 83.40 | 91.80 | 96.61 | 97.96 | 18.24 | 34.04 | 100 | 100 | 100 | 97.97 |
Count per 100 ml. | - | — | — | 0.9 | 0.3 | 0.1 | 0.1 | 11.5 | 6.3 | — | — | — | — |
Escherichia coli count Per cent samples negative in 100 ml | - | 100 | 99.20 | 99.57 | 99.18 | 98.31 | 98.47 | 32.70 | 50.35 | 100 | 100 | 100 | 99.49 |
Count per 100 ml | -_ | — | — | — | — | 0.1 | 0.1 | 5 | 3.6 | — | — | — | — |
After Treatment Number of Samples | 1,873 | 256 | 255 | 247 | 255 | 254 | 253 | 198 | |||||
Agar plate count per ml. 20-24 hours at 37°C. | 12.5 | 0.1 | - | 0.1 | - | 1.2 | 0.7 | - | |||||
3 days at 22°C. | — | 4 | 5 | 4 | 15 | 5 | 20 | 45 | |||||
Coliform count Per cent samples negative in 100 ml | 99.41 | 100 | 98.43 | 100 | 99.22 | 100 | 99.21 | 99.48 | |||||
E. coli count Per cent samples negative in 100 ml | 99.47 | 100 | 100 | 100 | 100 | 100 | 99.21 | 100 |