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(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 the analytical
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 any 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, 1970, was 235,040.
(ii) No houses were permanently supplied by standpipe.
(d) No artificial fluoride is being 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 Lea-derived via Lea Bridge Works, and well water from Chingford Mill pumping
stations. A small area of Lower Chingford adjoining Sewardstone Road north of Kings
Head Hill is supplied with River Thames-derived water. Between May and September
much of Walthamstow and parts of Chingford receive River Lea-derived water from
Coppermills Works.
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 shown to be not 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.
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