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 Lewisham Borough]
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Average results of the examination of the water supply to the Borough of Lewisham for 1948
PARTS PER MILLION (unless otherwise stated)
(a) CHEMICAL Table 10
Description of the sample | No. of samples | Ammoniacal nitrogen | Albuminoid nitrogen | Oxidised nitrogen | Chlorides as Cl. | Oxygen abs. from Permanganate (3 hrs. at 80°F) | Hardness (total) | Hardness (permanent) | pH. value | Conductivity |
---|---|---|---|---|---|---|---|---|---|---|
Deptford well | 4 | 0.002 | 0.024 | 5.1 | 33.9 | 0.16 | 354 | 150 | 7.2 | 625 |
Wilmington wells | 8 | 0.007 | 0.018 | 6.0 | 20.4 | 0.14 | 312 | 79 | 7.1 | 475 |
Darenth well | 5 | 0.001 | 0.012 | 3.5 | 16.4 | 0.15 | 301 | 96 | 7.1 | 450 |
Bexley well | 3 | 0.003 | 0.015 | 4.2 | 16.7 | 0.14 | 310 | 80 | 7.1 | 475 |
Shortlands wells | 3 | 0.000 | 0.024 | 4.5 | 19.0 | 0.15 | 315 | 129 | 7.2 | 475 |
Hampton (Thames filtered) | 250 | 0.097 | 0.080 | 3.8 | 27.5 | 0.96 | 248 | 71 | 7.7 | 475 |
Surbiton (Thames filtered) | 504 | 0.131 | 0.086 | 3.3 | 28.7 | 1 .07 | 227 | 69 | 7.6 | 450 |
Walton (Thames filtered) | 252 | 0.043 | 0.097 | 4.4 | 28.7 | 1 .18 | 237 | 72 | 7.6 | 450 |
(b) BACTERIOLOGICAL Table 11
No. of samples | Agar colony count | Percentage of samples negative 100 ml. | Bact. coli per 100 ml. | |
---|---|---|---|---|
Deptford well | 258 | — | 100.0 | Nil |
Wilmington wells | 404 | — | 100.0 | Nil |
Darenth well | 257 | — | 100.0 | Nil |
Bexley well | 253 | — | 100.0 | Nil |
Shortlands wells | 255 | — | 100.0 | Nil |
Hampton (Thames filtered) | 1,065 | 4.7 | 100.0 | Nil |
Surbiton (Thames filtered) | 516 | 7.3 | 98.3 | 0.035 |
Walton (Thames filtered) | 258 | 14.8 | 100.0 | Nil |