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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 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, 1969 was 176,586.
(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 water from Hampton 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
page 62.
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.
3 a) During the year, 90 samples of swimming bath water were taken from the
six public pools in the Borough and were submitted for bacteriological exam'
ination to the Public Health Laboratory Service. The recommended standard
is that 75% of samples should have a. colony count of less than 10 per ml.,
the remainder less than 100. 81 samples were satisfactory and 5 of the
remainder were only slightly below the recommended standard. Repeat
samples produced satisfactory results.
b) Nineteen samples of swimming bath water were taken from school or pri'
vately owned pools. Five were below the recommended standard but the
variation in two of these samples was very small. Repeat samples proved
bacteriologically satisfactory. (See page 91—Swimming Pools).
c) Three samples of well water were submitted for bacteriological examination
and were satisfactory.
d) Six samples of mains water thought to be causing illness or to be abnormal
in taste were submitted for bacteriological examination. All were satisfactory.
SEWERAGE & SEWAGE DISPOSAL
I am obliged to (a) Mr. M. S. Hebron, B.Sc., C.Eng., M.I.C.E., A.M.I.Mun.E.,
Borough Engineer and Surveyor, and (b) Mr. L. H. Thompson, A.M.I.C.E., A.M I S.P.
Regional Engineer, Greater London Council for the following reports:—
"(a) Sewerage
The work of replacing the compressed air ejectors by electrical pumps at Red Lion
Square, Hampton has been completed and similar work will be in hand in the near
future for two further pumping stations in Hampton Wick.
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