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(a) Physical Examination
Colour Light blue Taste none
Appearance Bright and clear Smell none
(b) Chemical Examination in parts per million
Total solid residue (dried at 180°C.) 200
Chlorine present as chloride 18.5
Ammonia, free 0.01
Ammonia, Albuminoid 0.00
Nitrate nitrogen 9.2
Nitrite nitrogen 0.14
Oxygen absorbed from (a) in 4 hours 0.10
permanganate solution (b) in 15 mins –
Hardness, as CaC03—Temporary 57
Permanent 54
Total 111
Alkalinity, as CaCO3 57
Free carbon dioxide, as C02 –
Iron absent
Other metals absent
Residual chlorine 0.15
Electric Conductivity at 20 °C 265 units
pH. 7.6
(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
attractive in appearance. It shows no significant alteration in chemical composition
as compared with previous samples from the same source.
The residual chlorine indicates adequate precautionary treatment.
The bacteriological condition of the water is excellent.
As judged by this sample the water is pure and wholesome and suitable for the
public supply.
The average hardness of the samples taken by the local authorities
was 8.3° compared with 8.8° in 1956 and 9.18° in 1955.
Drainage and Sewerage
Construction of the soil relief sewer in Woodmansterne Road referred
to in last year's report was completed.
311 Drainage obstructions affecting 943 houses were dealt with during
the year.
Rivers and Streams
The County Council has the responsibility for maintaining the flow
and purity of the River Wandle under the powers of its 1925 Act. The
usual work of maintenance was carried out during the year.
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