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(a) Physical Examination
Colour Faint blue Taste normal
Appearance Settled water bright and clear Smell none
Trace of white deposit
(b) Chemical Examination in parts per million
Total solid residue (dried at 180°C.) 210
Chlorine present as chloride 19.5
Ammonia, free 0.01
Ammonia, Albuminoid 0.01
Nitrate nitrogen 11.2
Nitrite nitrogen 0.01
Oxygen absorbed from (a) in 4 hours 0.12
permanganate solution (b) in 15 mins —
Hardness, as CaC03—Temporary 78
Permanent 53
Total 131
Alkalinity, as CaCO3 78
Free carbon dioxide, as CO2 —
Iron absent
Other metals absent
Residual chlorine 0.03
Electric Conductivity at 20 °C 290 units
pH. 7.3
(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. 0
Bacteria of indication enumeration:—
Organisms of the coliform group 0 per 100 ml.
Streptococci 0 „
CI. welchii 0 „
Remarks
This water is of good organic purity, moderate hardness and salinity and is
free from contaminating metals. The slight trace of white deposit which separates
from the water on standing consists of chalk only.
The bacteriological condition of the water is excellent.
As judged by this sample the water is pure and wholesome and is suitable for
the public supply.
The average hardness of the samples taken by the local authorities
excluding the two which were not representative was 8.4°.
Drainage and Sewerage
The routine work of maintenance of soil and surface sewers was
carried out, but there were no major works of reconstruction. A number
of soakaways were enlarged in size.
Three hundred and sixty-two drainage obstructions affecting 1,116
houses were dealt with during the year.
Rivers and Streams
The County Council who have the responsibility for its maintenance,
execute periodic clearing work on the River Wandle. An improvement
scheme, to which all the Surrey Authorities in whose districts the River
flows have agreed in principal, is now being prepared by the County
Council. This is designed primarily to prevent flooding which mainly
affects the districts lower down the River. A certain amount of work will
be called for in the Carshalton stretch but this will not be extensive.
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