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No. of Samples All Thames Derived
Ammoniacal Nitrogen 0.024
Albuminoid Nitrogen 0.089
Nitrate Nitrogen 4.1
Chlorides as Chlorine 30
Oxygen abs. from Permangenate 4 hrs. at 27 C. 1.12
Turbidity (Units) 0.1
Colour (Burgess Units) 12
Hardness (Total) 282
Hardness (non-carbonate) 73
pH Value 7.9
Phosphate as P04 1.9
Silicate as Si02 10
Sulphate as S04 64
Magnesium as Mg 5
Natural Fluoride as F 0.30
Surface Active Material as Manoxol O.T. 0.01
Electrical Conductivity (Micromhos) 590
Sodium Fbtassium as Na. 22.5
Sodium fbtassium as K 5.1
&cteriological Examinations:
No. of samples 3578
Agar plate count per ml: 20-24 hrs. at 37 C 12.2
Coliform count: Per cent, samples negative in 100 ml. 99.75
E. coli-count: Per cent, samples negative in 100 ml. 99.97
No new sources of supply were instituted and there were no changes to the general scheme
of supply in the area.
All new and repaired mains are disinfected with chlorine. After a predetermined period of
contact the pipes are flushed out and refilled; samples of water are then collected from these
treated mains; and the mains are returned to service only after results are found to be satisfactory.
The quality control from these laboratories is carried out by means of daily sampling from
sources of supply, from the treatment works or well stations, from the distribution system, and
through to the consumer. Any sign of contamination or any other abnormality is immediately investigated.
No houses were permanently supplied by standpipe.
No fluoride was added, and where the fluoride content is indicated in the analyses it
represents the naturally occurring fluoride in the water.
The Board's river and well sources have not been considered to have a plumbo-solvent
action, on account of their hardness content and alkaline reaction. It should, however, be appreciated that all types of water pick up varying amounts of metal from piping, particularly when
it is newly installed; this applies to copper, zinc, iron and also lead.
Tests for lead have been carried out in connection with chemical analysis of samples of
running water collected from premises in the distribution system and I set out below the information obtained over the period 1st January to 31st December, 1967:-