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10
In addition to these precautions camples of both the unchlorinated
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 624 such samples were taken and
examined. Of these, 245 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. 32 such samples were taken.
Bacteriological examinations of the untreated water showed
that, under normal conditions, the wells produce a water of remarkable
purity. Only at times of serious flooding by the river Thames
is a temporary deterioration sometimes observed. Under the present
arrangements this can readily be dealt with by shutting down the
wells concerned for a few days.
There have been complaints that the water tastes of chlorine.
Every effort is made to reduce this to a minimum but this nuisance
cannot be entirely eliminated unless new and very expensive apparatus
is installed.
Fortunately the proportion of residents who are unduly
sensitive to the taste is not large and I am able to say, with confidence,
that the small quantity of chlorine is quite harmless and that
the water supply is wholesome in every respect.
Richmond water contains 30 parts per 100.000 of hardness and
is not plumbo-solvent.
(b) The supply of the Metropolitan Water Board is received
in bulk through six connections off the 30 inch M.W.B. main.
The source of the water is the River Thames abstracted at
Wraysbury, Laleham and Walton intakes and stored in the Thames
Valley reservoirs. After storage the water is treated at the filtration
works at Hampton and Surbiton.
All the water is chlorinated before it leaves the works and
adequate contact to ensure complete action has been provided at
Hampton by the building of a contact tank which first came into
operation in July, 1948. Since the 19th October the filtered water