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211
"You will understand that this information does not relate to
private supplies or to supplies derived from or through other Water
Undertakings (if any).
(1) (a) The supply was satisfactory both as to (i) quality and
(ii) quantity throughout 1969.
(b) All new and repaired mains are disinfected with chlorine,
after a predetermined period of contact the pipes are
flushed out and refilled; samples of water are then collected
from these treated mains; and the mains are returned to
service only after results are found to be satisfactory.
The quality control from these laboratories is carried out
by means of daily sampling from sources of supply, from
the treatment works or well stations, from the distribution
system, and through to the consumer. Any sign of contamination
or other abnormality is immediately investigated.
(c) (i) The Board has no record of the number of structurally
separate dwellings supplied in your area, but the population
supplied direct according to the Registrar-General's
estimates at 30th June, 1969, was 228,030.
(ii) No houses were permanently supplied by standpipe.
(d) No artificial fluoride was added, and where the fluoride
content is indicated in the analyses it represents the
naturally occurring fluoride in the water.
(2) (a) The supply was derived from the following works and
pumping stations :-
River Thames—derived, also well water from Bexley,
Crayford, Darenth, Deptford, Wansunt and Wilmington
Pumping Stations.
No new sources of supply were instituted and there were
no changes to the general scheme of supply in your area.
The number of samples collected and the bacteriological
and chemical analyses of the supply from the above
sources after treatment are shown on the attached sheets.
(b) On account of their hardness content and alkaline reaction
the Board's river and well water supplies are not considered
to be plumbo-solvent. It should, however, be
appreciated that all types of water pick up varying
amounts of metal from the material of water piping
particularly when it is newly installed; this applies to
copper, zinc, iron and also to lead. Surveys carried out
between 1966 and 1968 on analyses of water from consumers'
premises confirmed this statement."