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Twenty-four reports from a firm of independent chemists employed
by the Company on samples of the finished water pumped into supply
from the Sutton and Woodmansterne stations, 12 from each were all
satisfactory. The public health departments of the five local authorities
in the supply area took 13 chemical and 27 bacteriological samples of
water as it reached the consumer and these too were also satisfactory.
The following is the report on a representative sample taken in the Urban
District:—
(a) Physical Examination
Colour Faint blue Taste normal
Appearance Bright and clear Smell none
Electric Conductivity at 20°C 300 Units
pH 7.6
(b) Chemical Examination in parts per million
Total solid residue (dried at 180°C.) 235
Chlorine present as chloride 19.5
Ammonia, free 0.00
Ammonia, Albuminoid 0.00
Nitrate nitrogen 13.7
Nitrite nitrogen 0.02
Oxygen absorbed from (a) in 4 hours 0.08
permanganate solution (b) in 15 mins. -
Hardness, as CaCOa—Temporary 67
Permanent 69
Total 136
Alkalinity, as CaC03 67
Free carbon dioxide, as COa -
Iron none
Other metals none
Residual chlorine 0.08
(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 in 100 ml.
Streptococci 0 do.
CI. welchii 0 do.
Remarks
This water is attractive in appearance, of good organic purity and is free from
contaminating metals. It is of moderate hardness and salinity. The residual chlorine
indicates that adequate precautionery treatment is being maintained.
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
The sewage of the district is pumped to the treatment works of the
Croydon Corporation in Beddington. Surface drainage in the southern
part of the district is mainly by soakaways into the chalk, in the northern
part it is drained to the River Wandle.
In addition to the routine maintenance, clearing and inspection of
the sewers and soakaways by the Engineer's Department, the following
modifications were made during the year:—
A short length of high level soil sewer between numbers 93 and
97, Woodmansterne Road was relayed.
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