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(ii) 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:—
Thames Valley Works and Stoke Newington Works. No new sources of supply were
instituted and there were no changes to the general scheme of supply in the area.
The number of samples collected and the bacteriological and chemical analyses of the
supply from the above sources after treatment are shown in Tables 18 and 19, page 87.
(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. Special tests for lead have been carried out during 1968 on 100
premises where a lead supply pipe is installed. The premises were chosen to give an
even distribution of samples throughout the whole of the Board's area. Two samples
were collected from each premises; one was the first running of water standing in the
lead pipe overnight and the other was a sample of water after running the tap for a
few minutes. The results are set out in Table 20, page 88.
These are very satisfactory and the figures are within the limits of the World Health
Organisation European Standards for Drinking Water Quality. This states that the
upper limit for lead in running water in the supply should not be more than 0.1 mg/l
(Pb); but where water undertakings continue to use lead piping the concentration of
lead (as Pb) should not exceed 0.3 mg/l after 16 hours contact with the pipes."
In the event of any suspicion of contaminated public mains water, the Metropolitan Water
Board is informed and investigations are made: if necessary, samples are taken for examination.
Complaints (which are extremely few) have usually referred to some alleged unusual taste.
In common with many of the London Borough Councils, the City Council is in favour of the
Metropolitan Water Board being asked to adjust the fluoride content of the public water supplies
to the optimum amount necessary to prevent dental caries.
Private Water Supplies—Deep Wells
The water from 68 boreholes is used for drinking and domestic purposes in 54 premises. Of this
number, 19 bores supply water to 18 premises occupied by Government departments or Crown
Agents and, where this obtains, arrangements for maintenance and examination are in the hands
of the Ministry of Public Building and Works and the Government Chemist.
During the year, in relation to the 49 boreholes in private ownership and control, 77 (83) samples
of water were submitted for bacteriological examination and 26 (26) for chemical analysis. One
of the bacteriological examinations indicated bacterial impurity including coliform bacteria in
considerable numbers. The borehole in question, one of two supplying one building, was not in
use at the time, having been the subject of recent overhaul and the contamination reflected the
disturbance occasioned by these works. Further tests established the resumption of a satisfactory
supply before this bore was brought into commission again.
All other examinations indicated satisfactory supplies.
Swimming Bath Water Examination
Monthly examinations of the water were carried out at each of the 11 municipal swimming
baths in the City. During the year, 210 (196) samples were submitted to the Public Health
Laboratory Service for bacteriological examination, and the same number of samples were examined
at the baths for residual chlorine and pH value.
In one instance the bacteriological examination indicated the probable presence of faecal
bacteria in minimal numbers, namely two per 100 millilitres. As the bath had not been used, and
there were no users at the time of sampling, this otherwise inexplicable contamination may have
been introduced by one of the long-handled squeegees with which the floor of the bath was being
cleansed. Attention was drawn to this possibility and subsequent examinations, in similar circumstances,
proved entirely satisfactory.
Offices, Shops and Railway Premises Act 1963
The Council is responsible for administering the general provisions of the Act in such premises
as are required to be registered with the local authority.