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44
WATER SUPPLY.
The Borough has a dual source of water supply:—
(1) The Metropolitan Water Board supplying an area
bounded on the West by the London Midland and Scottish
Railway, on the North by a line along the Mutton Brook to
Bridge Lane and on the East by the London North Eastern
Railway. The remaining Northern portion of the Borough
is supplied by the Colne Valley Water Company.
The Metropolitan Water Board supplies selected Thames
water which has been subjected to purification by storage in
Queen Mary Reservoir for two months, in which time it is
freed of the bulk of organisms. It is filtered through rapid
and then slow sand filters, attaining a degree of purity which
compares favourably with the general supplies in Great
Britain, but as a further safeguard, terminal chlorination
is applied which ensures a first class water in every respect.
The quality of standard water which Hendon has been receiving
for a definitely prolonged period is negative to Bact. coli
in 100 ml. and a colony count of less than 5 per ml. Sampling
of raw water, filtered water, mains water and all filter beds
in rotation are examined on every working day, and the condition
of the water in the reservoir is also kept under similar
surveillance.
(2) The Colne Valley Water Company derives the whole
of its supply from deep wells sunk into the chalk and before
distribution to the consumers the water is softened and
chlorinated. The treatment the water receives and the purity
of the supply are under the constant supervision of a resident
chemical and bacteriological staff which carries out examinations
in modern Laboratories situated at their Works.
The number of samples examined during the year by the
Colne Valley Water Company were as follows:—