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even distribution of samples throughout the whole of the Board's area.
Two samples were collected from each premises; one was the first running of
water standing in the lead pipe overnight and the other was a sample of
water after running the tap for a few minutes. The results are set out in
the following table:-
Lead content of water from main taps in
consumers premises
Lead content
(mg/1 Pb)
Samples of water
standing in lead
pipe overnight
Samples of water
after running the
tap
Less than 0.01
10
37
0.01
31
57
0.02
21
4
0.03
8
1
0.04
9
0
0.05
5
0
0.06
5
0
0.07
4
1
0.08
1
0
0.09
3
0
0.10
1
0
0.12
1
0
0.16
1
0
100 premises
100 premises
The above results are very satisfactory and the figures are within
the limits of the World Health Organisation European Standards for Drinking
Water Quality, This states that the upper limit for lead in running water
in the supply should not be more than 0.1 mg/1 (Pb); but where water undertakings
continue to use lead piping the concentration of lead (asPb) should
not exceed 0.3 mg/1 after 16 hours contact with the pipes.
Chemical Examinations (Milligrammes per litre unless otherwise stated).
All Thames derived
Ammoniacal Nitrogen
0 020
Albuminoid Notrogen
0.083
Nitrate Nitrogen
3.9
Oxygen abs, from KMn04 4 hrs. at 270C.
1.20
Hardness (total) CaCO3
280
Hardness (non-carbonate) CaCO3
76
Magnesium as Mg
4
Sodium as Na
23.2
Potassium as K
5.3
Chloride as CI
32
Phosphate as P04
2.0
Sillicate as SiO2
10
Sulphate as S04
62
Natural Fluoride as F
0.30
Surface active material as Manoxol OT
0.02
Turbidity units
0.1
Colour (Burgess units)
14
pH value
7.9
Electrical Conductivity (micromhos)
570
B.6