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24
Average results of the chemical and bacteriological examination of the water supply to the Borough of Lewisham for 1958
milligr ams per litre (unless otherwise stated)
(a) CHEMICAL
Table 18
Description of
the sample
Ammonia
nitrogen
Albuminoid
nitrogen
Oxidised
nitrogen
(nitrate)
Chlorides
as CI.
Oxygen abs.
from
permanganate
(4 hrs. at 27°C)
Hardness
(total)
Hardness
(noncarbonate)
pH
value
Electrical
Conductivity
(gem mhos)
Thames-derived filtered
water
0027
0077
4.2
26
1.26
270
66
7.9
550
Bexley Well
0005
0020
5.6
17
0.15
302
64
7.2
550
Darenth Well
Nil
0019
5.4
16
0.06
260
30
7.2
475
Darenth Bore Hole
0002
0023
5.9
17
0.08
274
38
7.2
525
Deptford Well
0005
0021
6.5
36
0.18
368
128
7.2
725
Shortlands No. 1
Nil
0017
5.1
17
0.03
278
60
7.2
525
Shortlands No. 2
Nil
0025
5.0
16
0.03
278
58
7.3
525
Shortlands No. 3
Nil
0020
5.2
18
0.05
284
72
7.3
550
Wilmington No. 1
0011
0 026
5.6
21
0.14
280
48
7.3
525
Wilmington No. 2
0009
0024
7.3
22
0.13
294
60
7.3
550
(b) BACTERIOLOGICAL
Table 19
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.
370 C.
(20-24
hrs.)
22° C.
(3 days)
370 C.
(20-24
hrs.)
22° C.
(3 days)
Coliform
E. Coli
Coliform
E. Coli
Thames derived filtered
water
9.7
99.07
99.88
Bexley Well
0.1
7.5
94.80
99.26
0.1
5.7
97.28
100.0
Darenth Well
0.3
7.8
87.95
99.20
Darenth Bore Hole
0.1
92.0
88.79
96.73
0.1
193.5
100.0
100.0
Deptford Well
0.1
2.1 .1
92.69
95.89
0.2
28.5
98.67
100.0
Shortlands No. 1
0.1
1.9
97.39
99.13
0.1
5.5
100.0
100.0
Shortlands No. 2
0.1
13.0
96.60
97.96
Shortlands No. 3
0.1
4.0
97.91
99.16
Wilmington No. 1
0.7
71.1
86.96
0.1
2.7
99.59
100.0
Wilmington No. 2
0.5
39.8
72.12
87.61