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. Since this report was written it is learned that —
(1) the London County Council have now two schemes in hand (one for the Northern Outfall
and the other for the Southern Outfall at a total cost for the two of £18 million) which
when completed, as hoped by 1965, should result in a sewage effluent up to "Royal
Commission" standards.
(2) the Ministry of Housing and Local Government have now given permission to the Metropolitan
Water Board to proceed with the construction of two new reservoirs.
(3) both these Committees have now completed their investigations and their reports are in
draft form.
TILBURY DOCK FRESH WATER SUPPLIES
In November a report was received from your Sanitary Inspector on the Tilbury Dock, Mr. D. E.
Madeley, that the fresh water main on the South Side of the dock had become contaminated with
salt water due, as subsequent enquiries showed, to a vessel having pumped dock water back
into the shore fresh water main for a number of hours.
Your Medical Officer, in reporting the incident, said that he had under consideration the
whole question of water supplies in the dock areas and would report further when the enquiries
had been completed but that meanwhile it was worth noting those details of ship construction
and routine which may make possible occurrences of this kind under certain circumstances.
As Mr. Madeley pointed out in his report most of the bigger and more modern ships have two
distinct and separate fire fighting systems
(1) A Fire-main system which is salt water piped at considerable pressure to all parts of the
ship. There are numerous connections to which fire hoses can be fitted. This is the
system which supplies the flush for water closets and the wash-deck service.
(2) Sprinkler system which is an automatic device for damping out fires in passenger and crew
spaces, etc. It is usually connected with some form of fire alarm. The pipes are numerous
and of small diameter. It is maintained with fresh water to minimise corrosion.
If, for any reason, the Fire-main pump is out of action in port it is possible to connect up with
a pump ashore to maintain a fire-fighting pressure in the system. For this purpose there is a
fire-main-"Shore to Ship" connection (in most ships more than one) with an Instantaneous Connection
such as is used by most English Fire Brigades.
If the smaller pump for the Sprinkler System is out of action it has been the practice to connect
the system with the shore fresh water supply to maintain the Sprinkler in action. This works
satisfactorily from a fire-fighting point of view since it provides the necessary pressure and
quantity required. The connection on deck for this purpose has a "Butterfly" union corresponding
to the type of fitting on the Port of London Authority's fresh water hose. It is usual to have
a non-return valve incorporated in the ship's connection as a precaution against returning ship's
water to the shore line.
In this particular incident, on Wednesday afternoon, the 16th November, instructions were
given on a certain ship in Tilbury Dock to connect the Sprinkler System with the shore fresh
water system. The connection was carried out by an inexperienced member of the crew who on
proceeding to the position on deck by No. 2 Hatch, observed the "Fire-main Shore to Ship"
connection plainly marked in red lettering. He apparently did not observe the "Sprinkler Shore
to Ship" connection a few feet away which is also marked in red lettering, but which lam
informed was obscured at the relevant time by an accumulation of dunnage on deck.
The man did, however, find that the connection on the Shore Fresh water hose (Butterfly type)
would not fit the ship's Fire-main Service connection (Instantaneous type). Instead, however,
of returning to his senior for further instructions he obtained an 'adaptor' (a short length of pipe
with a Butterfly connection at one end and an Instantaneous connection at the other end)and
with this he made the connection between the ship's salt water system and the shore fresh
water system.
When the valves were opened, salt water (from Tilbury Dock via the ship's pumps) was forced
into the fresh water mains. This continued the whole of Wednesday night and was not discovered
until Thursday morning. It was not reported to any Officer of the ship until much later when it
was found that the ship's own drinking water was brackish.
Your Sanitary Inspector on the Tilbury Dock did not get the full story until Saturday, 19th
November at about 5.0 p.m., after three days of most painstaking investigation into what had
seemed at first to be a most mysterious affair.
Two vessels were involved in the incident both taking water simultaneously along the same
water supply line.
One of the vessels involved was almost ready to put to sea, so the dirty water had to be
pumped out, after the tanks had been super-chlorinated. She left her berth in the dock and her
tanks were refilled with fresh water, (at considerable expense to the shipping company) supplied
by water boats while she was lying in Gravesend Reach.
Later Mr. Madeley confirmed that the cause of the pollution in the dock mains was due
to the supply hose from the dock hydrant having been directly connected, inadvertently,
to one of the vessel's fire lines instead of the "sprinkler system". The polluted water
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