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Copies of the reports of 36 examinations carried out during the year
by the firm of independent chemists for the Company have been received
at approximately monthly intervals. Twelve of these were in respect of
the Sutton finished water and a similar number were in respect both of
the Woodmansterne finished and the Cheam raw waters. All were
reported as wholesome and fit for the public supply except one raw
sample which was stated to be fit for treatment for the public supply.
The Public Health Authorities in the supply area arranged the examination
of 17 chemical and 28 bacteriological samples of the water as it
was delivered to the consumer and all were satisfactory. The following
is the report on a sample which is representative of this type of water.
(a) Physical Examination
Colour Faint blue Taste normal
Appearance Bright and clear Smell none
Electric Conductivity at 20°C 275 Units
pH 7.4
(b) Chemical Examination in parts per million
Total solid residue (dried at 180°C.) 210
Chlorine present as chloride 20.5
Ammonia, free 0.00
Ammonia, Albuminoid 0.005
Nitrate nitrogen 10.5
Nitrite nitrogen trace
Oxygen absorbed from (a) in 4 hours 0.06
permanganate solution (b) in 15 mins. —
Hardness, as CaCO3—Temporary 54
Permanent 66
Total 120
Alkalinity, as CaCO3 54
Free carbon dioxide, as CO2 —
Iron absent
Other metals absent
Residual chlorine none
(c) Bacteriological Examination
Number of colonies developing per millilitre of water:—
on agar in 2 days at 37°C. 0
on agar in 3 days at 22°C. 1
Bacteria of indication enumeration: —
Organisms of the coliform group 0 in 100 ml.
Streptococci 0 do.
Cl. welchii 0 do.
Remarks
This water is of good organic purity, moderate hardness and salinity and
attractive in appearance. It is free from contaminating metals and similar in
chemical composition to previous samples from the same source.
The bacteriological condition of the water is excellent.
As judged by this examination the water is pure and wholesome and is
suitable for the public supply.
Drainage and Sewerage
An extension to the soil sewer on the Woodcote Grove Estate has
been carried out and the relief surface water sewer in Culvers Avenue
referred to in last year's report has been completed.
Regular clearing and inspection of the sewers and maintenance of
the soakaways was carried out as routine and repairs executed to gullies,
frames and manhole covers by the Engineer's Department.
Two hundred and sixty-seven drainage obstructions affecting 938
houses were dealt with mostly in combined systems.
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