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28
Water supply
I am indebted to the Director of Water Examination of the
Metropolitan Water Board for the information on which the following
report on Lewisham's water supply is based.
The water supply to Lewisham is divided into three zones : the
low zone is supplied from Deptford Well and by Thames-derived
filtered water ; the Eltham zone is supplied from Wilmington, Darenth
and Bexley Wells and should the occasion arise, with a small proportion
from the low zone ; the Bromley zone to the south of the borough is
supplied from Shortlands Well and again on occasions with additional
Thames-derived filtered water.
River Thames water is abstracted at the Board's intakes at Walton,
Laleham and Wraysbury and is stored in the Board's reservoirs at
Walton, Littleton and Staines. The water is filtered at Hampton,
Surbiton and Walton works. Contact tanks have been built at
Hampton and Walton where there is opportunity for chlorine to exert
its full effect before the water is pumped into supply and thereby
chlorinous and other tastes are to a great extent avoided. The dose
of chlorine at these stations is now controlled automatically in regard
to changes in quality of the filtered water as well as to changes in rate
of flow.
All the well water is chlorinated and here also contact tanks are
provided. Finally, any residual chlorine is completely removed or
reduced to a level that would not be noticeable to consumers before
the water leaves the works.
Bacteriological analyses are made at least five times a week and in
the case of the river-derived supplies, the water is analysed at all stages
of purification. All new and repaired mains are chlorinated before being
restored to use and samples are collected for analyses to establish that
the quality of the water is up to the standard normally supplied.
None of the supplies is plumbo-solvent.
Appended are the average results of the chemical and bacteriological
analyses of the various supplies as forwarded by the Metropolitan
Water Board :—