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Water as delivered to the consumer is examined monthly by the
Counties Public Health Laboratory on behalf of the Company and a
further 13 chemical and 26 bacteriological samples were examined by
the Public Health Departments in the supply area. All were satisfactory.
The following is a representative analysis:—
Chemical analysis in parts per million.
Total solid matter in solution (dried at 180°C.) 220
Combined chlorine 20.9
Nitric nitrogen 12.0
Nitrous nitrogen 0.08
Ammonia, free and saline 0.030
Ammonia, albuminoid 0.035
Oxygen absorbed from permanganate in 4 hours at 26.7°C. 0.14
Hardness—by acidimetric titration—Temporary 54
Permanent 73
Total 127
Reaction for free chlorine:—positive, equivalent to 0.09
pH 8.3
The water was bright and clear and was normal in colour.
Bacteriological examination.
Action by free chlorine during transit of the sample was prevented
at the time of sampling.
Number of colonies per ml. developing upon agar in 2 days at 37 C. 0
Number of colonies per ml. developing upon agar in 3 days at 22 C. 0
Organisms of the coliform group absent in 100 ml.
Streptococci do.
CI. welchii do.
This water is of good organic purity and very moderate hardness. The
changes noted in the previous chemical sample taken on the 19th April, 1951,
have been very largely reversed, although the temporary hardness is still slightly
higher than the permanent. The reaction (pH) although slightly alkaline is now
at a satisfactory level.
The residual chlorine indicates that treatment is being maintained.
The bacteriological condition is excellent and, as judged by these samples,
the water is pure and wholesome and suitable for the public supply.
Drainage and Sewerage.
No extensions or replacements have been made to the sewerage
system, but a private drain has been laid which connects the buildings
in the War Memorial Sports Ground into the drainage system of Carshalton
West County Secondary School and subsequently into the Council's
sewerage system.
A start has been made in the construction of two deep manholes
in Blakehall Road and two deep manholes in Grosvenor Avenue on one
of the trunk sewers to facilitate maintenance.
Sewage is pumped to the disposal works of the Croydon Corporation
in Beddington, except at various points on the fringes of the district,
where it is more conveniently drained to the sewage systems of neighbouring
authorities.
Surface drainage in the south is mainly by soakaways in the chalk ;
elsewhere it is by surface sewers to the River Wandle.
Three hundred and one drainage obstructions, affecting 1,082
houses were dealt with.
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