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11
SECTION C—SANITARY CIRCUMSTANCES.
Water Supply.
Richmond has two separate sources of drinking water:—
(a) From local wells.
(b) From the Metropolitan Water Board.
(a) The local supply comes from the deep well in the Terrace
Gardens, from two shallow wells in the Old Deer Park, and from
two shallow wells in Petersham. Water from all these wells is
pumped to the low level reservoir at Petersham where it undergoes
controlled chlorination. It takes two to four hours to pass through
the reservoir and is then pumped to the high level reservoir in
Richmond Park where it remains for 24 hours before passing into
public supply.
Estimations of the amount of free chlorine in the water issuing
from the low level reservoir are carried out every two hours by day
and night by the staff of Petersham Pumping Station. In addition
the free chlorine is continuously recorded by mechanical means at
the Petersham Pumping Station and at the Old Works, Water Lane.
It has been found that, to ensure a safe and wholesome supply dosage
with chlorine must be maintained so as to provide between 0.4 and
0.5 parts per million free chlorine in the water issuing from the low
level reservoir. After 24 hours contact in Richmond Park reservoir
the free chlorine content is reduced to 0.15 p.p.m. and, by the time
it reaches the consumer the free chlorine content is about 0.1 p.p.m.
In addition to these precautions samples of both the unchlorin'
ated well waters and the chlorinated water passing into public supply
are taken at regular intervals for bacteriological, physical and
chemical examination.
During the year no less than 581 such samples were taken and
examined. Of these 296 were samples of chlorinated water passing
into public supply; everyone of these was free from coliform organisms
and of a very high standard of purity.
Chemical examinations of the water from individual wells now
in use, showed that the organic quality remained entirely satisfactory
throughout the year. 23 such samples were taken.