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London County Council.
Report of the Medical Officer on the Report of the Royal Commission on
Metropolitan Water Supply, 1892-3,
(Printed by order of the Water Committee, 18th January, 1894.)
The instruction to the Royal Commission on the Water Supply of the Metropolis was to enquire
whether the present sources of supply of the metropolitan water companies were adequate in quantity
and quality.
The instruction of the Committee to myself is to discuss the report of the Royal Commission,
and in doing so I propose to limit my observations to that portion of the report which relates to the
quality of the present sources of supply, a subject upon which the Commission received a large amount
of valuable though occasionally conflicting evidence.
I may say at the outset that I fully recognise that the report and conclusions of the Commission
are entitled to the greatest respect, but in discussing some of the points which are dwelt upon in that
report, I desire to emphasize certain aspects of the case which I think may properly be submitted for
the consideration of the Committee.
The Royal Commission had before it evidence submitted by the medical men, who, acting under
the instructions of the County Council, had inspected the Thames and Lea, and their tributaries. This
evidence showed that the rivers from which the water companies draw their supplies receive from the
towns situated on their banks, at varying distances above the intakes, sewage effluents which, after
treatment of the sewage, either by filtration through land, or by chemical processes, enter the rivers. In
addition to these, numerous pollutions from smaller populations discharging into cesspools and ditches
reach, untreated, the streams at times of heavy rainfall. Such sewage must, not infrequently, contain
the excremental matter of persons suffering from typhoid fever, and may not improbably in the future
contain from time to time the excreta of persons suffering from cholera. The virus of both these
diseases has been found by past experience to have been disseminated by water, and to have produced
fatal results in persons drinking such water.
Nevertheless, the Commission reports, "we are strongly of opinion that the water as supplied to
the consumer in London is of a very high standard of excellence and purity, and that it is suitable in
quality for all household purposes. We are well aware that a certain prejudice exists against the use
of drinking water derived from the Thames and Lea, because these rivers are liable to pollutions,
however perfect the subsequent purification by natural or artificial means may be ; but, having regard
to the experience of London during the last thirty years, and to the evidence given to us on the
subject, we do not believe that any danger exists of the spread of disease by the use of this water,
provided that there is adequate storage and that the water is efficiently filtered before delivery to the
consumers "
The report of the Commission is in the main devoted to a discussion of the risks to the water
consumer from the two diseases I have mentioned, and for practical purposes it is not necessary at the
present time to go beyond them. Not only are these diseases known to be water-borne, but experience
has shown that a very small amount of the excremental matter of persons suffering from them is
capable under favourable circumstances of infecting vast volumes of water, thereby causing disastrous
results to persons who consume water thus polluted. There are very strong grounds for thinking that
these maladies are caused by micro-organisms contained in the excreta, and there is much reason for
believing that certain micro-organisms, which have been identified and studied, are the essential
elements which cause these diseases.
It is shown in the report of the Royal Commission that the following circumstances contribute
to the safety of the London consumer—
The apparent inability of the organisms of cholera and enteric fever to live for long periods outside
the animal body in which they have been developed.
The fact that they multiply by fission and not by the formation of spores, which are peculiarly
resistant to hostile influences.
The dilution to which the polluting matter reaching the rivers is subject, and especially at times
of flood, by the large amount of fluid with which it is admixed.
The action of light, of low temperature and of vegetable organisms to which the organisms in the
polluting matter are exposed in the river, and which are known to be prejudicial to their existence.
The fact that floods occur preferentially in the winter when the temperature is low.
The length of flow of the rivers, between the points at which they receive the pollutions and
those at which the water is taken for public consumption. This gives opportunity for subsidence, and
for light and for river organisms to act deleteriously upon such disease-producing organisms as may be
present in the water.
The treatment by the water companies of this water by subsidence and filtration, both of which
contribute materially to free the water supplied to the consumer from organisms of all kinds.
Evidence was received by the Commission which tended to show the large powers possessed by
running waters of freeing themselves from pollution. It would serve no useful purpose to discuss this
evidence in any detail ; the fact may be accepted that these powers exist, and are operating in the
Thames and Lea to an extent which contributes in no small degree to the safety of the London water
consumer. There are, however, a few points to which brief reference must be made.