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representatives of the Ministry of Health, London County Council, Society
of Medical Officers of Health and Medical Officers of the Metropolitan
Boroughs, were present.
The Director of Water Examination to the Metropolitan Water
Board gave an account of the occurrences which led up to the present
situation, arising from extensive floods.
As a result, and to implement the action already being taken
by your Officers in the areas affected, your Medical Officer issued the
following detailed instructions;-
Memorandum to all Inspectors.
I have been informed by the Metropolitan Water Board that the
River Lea water has gained access to the mains and that, in consequence,
the water supply to the above-mentioned docks is contaminated and
should not be used for drinking purposes unless boiled or chlorinated.
In the case of ships proposing to take on water for drinking,
chlorination cannot be adequately carried out on shore and recourse
must, therefore, be had to the chlorination of water tin. ship's tanks.
For this purpose ships may be divided into four categories:
(1) British Foreign-going vessels.
(21 Foreign vessels.
f3) Coastwise.
(U; Water Barges.
British Foreign-going vessels are required to carry a supply of
stabilised chloride of lime (bleaching powder) in their medical scales
and use should be made of this supply to carry out chlorination of
water that is being taken on board.
The following is the method of using the powder -
The purifying powder when mixed with drinking water in a proportion
of 1 part of the powder in 250,000 parts of water has the effect of
destroying all organisms in the water, and the object, therefore, is to
make a solution of this strength in the water in the tanks.
Proceed at follows:
First estimate the quantity of water which you require to purify
and note that if the tank is party full before filling begins, enough
powder must be added not only to sterilise the quantity of water that
is being poured into the tank, but also any water that is already in
the tank. Thus if the tank contains 1,500 gallons of water before
filling and 3,000 gallons are taken in from the shore, sufficient
powder must be added to purify U,5000 gallons.
The measure with which you are provided holds exactly 60 grains
or one-eighth of an ounce, and this quantity is sufficient to purify
200 gallons of water. The following table will assist you to
estimate the number of gallons of water in terms of cubic feet or tons;-
36 cubic feet of water - 22i+ gallons - i ton.
\ ton - 112 gallons - 18 cubic feet.
1,500 gallons -6.7 tons - 2U0 cubic feet.
Each tank must be dealt with separately.
Having decided upon the quantity of powder yOu require for each
tank, take the measure provided for the purpose and measure out the
necessary amount of powder, pouring each measureful on to a piece of
clean paper. Take the powder and pour it into the tank whilst
filling is proceeding. The tank should be about quarter full when
this is done. The water in the tanks must not be used for drinking
until at least one hour has elapsed. If the water is used too soon,
there may be a slight smell and the taste of chlorine in it. You may
rest assured that this smell and taste cannot exert any harmful effect
whatever on anybody drinking the water. The taste may persist if the
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