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Table 71
Average results of the chemical examination of the water supplied to the Borough of Lewisham
Milligrammes per litre (unless otherwise stated)
Description of
the Sample
Number of Samples
Day of the month
Ammoniacal
Nitrogen
Albuminoid
Nitrogen
Nitrate
Nitrogen
Oxygen abs. from
KMnO4 4 hrs. at
27° C.
B.O.D. 5 days
at 20° C.
Hardness (total)
CaCO3
Hardness (noncarbonate)
CaCO3
Magnesium
as Mg
Sodium
as Na
Potassium
as K
Chloride as CI
Phosphate as PO4
Silicate as SiO2
Sulphate as SO4
Natural Fluoride as F
Surface-active material
as Manoxol OT
CO2
Turbidity units
Colour (Burgess units)
pH value
Electrical Conductivity
(micromhos)
All Thames-derived
363
0.024
0.089
4.1
1.12
—
282
73
5
22.5
5.1
30
1.9
10
64
0.30
0.01
0.1
12
7.9
590
Deptford
4
0.013
0.053
6.7
0.08
—
373
131
8
26
5.5
42
104
0.30
39
0.0
1
7.1
740
Wilmington
4
0.008
0.037
7.3
0.15
—
286
54
3
16.0
2.5
26
26
0.20
33
0.2
1
7.3
590
Darenth
4
0.009
0.033
4.7
0.10
—
270
46
2
11.0
1.9
18
24
0.15
24
0.0
0
7.3
510
Bexley
5
0.006
0.030
5.4
0.10
—
331
89
4
14.0
2.4
20
56
0.20
34
0.0
1
7.2
600
82