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48
SANITARY CIRCUMSTANCES OF THE AREA
WATER
Supply
Apart from the houses in three roads in the south-west part of the
district (Wood End Avenue, Wood End Road, and Westwood Avenue),
which are supplied by the Rickmansworth and Uxbridge Valley Water
Company, the area is supplied with water by the Colne Valley Water
Company.
Up to the middle of the last century many of the areas which now
form part of Greater London had no piped water supply. In 1873,
the Company was incorporated to supply the parishes of Bushey,
Aldenham and Elstree, Stanmore, Pinner, Kingsbury and parts of
Harrow-on-the-Hill and Hendon. A well was sunk at Bushey and the
first supplies given in 1876. In 1885, the Company acquired the Harrow
Water Works Company. In 1894 they acquired the Central Middlesex
Water Company Limited, taking over the supply of water to those parts
of the parish of Harrow-on-the-Hill not up to then within the limits of
supply, and also the supply to Alperton, Sudbury and parts of Wembley.
The area supplied has remained largely unchanged; the demand though
has increased markedly as the result of building. The area supplied is
some 51 square miles in Middlesex and 30 square miles in Hertfordshire.
The population of over half a million receives an average of 30 gallons
per head per day, the combined demand for domestic and industrial
purposes being over 23 million gallons a day.
Nearly all this water is obtained from a series of wells with adits
driven into the Upper and Middle Chalk along the valley of the river
Colne, the water originating in the gathering grounds in the Chilterns.
The main pumping stations are at Aldenham Road, Bushey, Eastbury
(between Watford and Northwood) and Berrygrove (2 miles north of
Bushey). During the last war supplies were augmented from wells at
Ruislip Common and Poors Field, and in the immediate post-war years
by wells north of the Berrygrove well at Wall Hall, Brickett Wood and
Netherwild Farm. There is also a well at Bessborough Road, Harrow,
which originally belonged to the Harrow Water Works Company.
The water from these wells and adits is lifted to the surface by deep
well pumps. After treatment most is then pumped into surface reservoirs
at Windmill Lane, Bushey Heath, the highest point in the area
supplied by the Company. From these reservoirs the water is distributed
by gravity through some 300 miles of trunk mains and 650 miles of
distribution mains. A boosting station at Grove Hill Road ensures
adequate pressure on Harrow Hill.
The water is treated by softening, partly by Clark's lime process,
part by the method of base exchange, and is then chlorinated.
The Colne Valley Water Company is at present "carrying out a
major programme of new capital works in order to be in a position to
meet the increasing demands for water throughout the 81 square miles
supplied by the Company. The new works include a very large treatment
and softening plant. It has since the inception of the Company
been the policy to soften the water supplied and that policy remains