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
Lewisham 1959
[Report of the Medical Officer of Health for Lewisham Borough]
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26
Average results of the chemical and bacteriological examination of the water supply to the Borough of Lewisham for 1959
milligrams per litre (unless otherwise stated)
(a) CHEMICAL
Table 20
| Description of the sample | Ammonia nitrogen | Albuminoid nitrogen | Oxidised nitrogen (nitrate) | Chlorides as C1. | Oxygen abs. from permanganate (4 hrs. at 27°C) | Hardness (total) | Hardness (non-carbonate) | pH value | Electrical Conductivity (gemmhos) |
|---|---|---|---|---|---|---|---|---|---|
| Thames-derived filtered water | .022 | .075 | 3.8 | 28 | 1.08 | 250 | 56 | 7.7 | 525 |
| Deptford | .010 | .033 | 8.3 | 37 | 0.18 | 374 | 142 | 7.0 | 750 |
| Bexley | .008 | .031 | 5.4 | 18 | 0.10 | 298 | 60 | 7.2 | 575 |
| Darenth | .010 | .024 | 5.6 | 17 | 0.08 | 266 | 36 | 7.2 | 500 |
| Wilmington | .012 | .026 | 8.5 | 22 | 0.08 | 288 | 58 | 7.1 | 550 |
(b) BACTERIOLOGICAL Table 21
| BEFORE CHLORINATION (RAW WATER) | AFTER CHLORINATION (WATER PASSING INTO SUPPLY) | |||||||
|---|---|---|---|---|---|---|---|---|
| Plate counts (average per ml.) Colonies counted on agar | Coliform count | Plate counts (average per ml.) Colonies counted on agar | Coliform count | |||||
| Percentage samples neg. 100 ml. | Percentage samples neg. 100 ml. | |||||||
| 37ºC. (20-24 hrs.) | 22º C. (3 days) | Coliform | E. Coli | 37ºC. (20-24 hrs.) | 22º C. (3 days) | Coliform | E. Coli | |
| Thames derived filtered water | - | - | - | - | 6.7 | - | 100.00 | 100.0 |
| Deptford | 18.7 | 217 | 97.07 | 99.51 | 0.2 | 5 | 99.53 | 100.0 |
| Bexley | 1.0 | 4 | 99.20 | 100.00 | 0.3 | 2 | 99.32 | 100.0 |
| Darenth | 0.2 | 3 | 96.58 | 100.00 | 0.1 | 8 | 100.00 | 100.0 |
| Darenth Borehole | 0.1 | 56 | 86.76 | 99.09 | ||||
| Wilmington No. 1 Well | 0.7 | 44 | 75.91 | 95.62 | 0.1 | 2 | 99.61 | 99.6 |
| Wilmington No 2. Well | 2.0 | 95 | 86.18 | 96.06 | ||||