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employee with the result that circulating dock water in the fire-fighting and ballast line overcame
the pressure in the entire fresh water ring main of the dock and polluted, not only the supply to the
offending ship but to neighbouring ships and shore premises alike. To reinstate the potable water
supply was indeed a major operation and heavy economic losses were substantially cut by the
Services of efficient water boats and with the complete co-operation of all concerned. It was not
until after the pollution had become widespread and extensive investigation had been carried out
that the culprit admitted his guilt.
Indirect. Supply via water barge should, in theory, increase the risk of pollution but in practice
this has not been the case in London, and of recent years the results of analysis have been consistently
"excellent". These results apply to single skin steel constructed barges which are,
however, never allowed to "ground" between overhauls. This is a great improvement from the bad
old days when a barge was only three parts filled from the main and then allowed to "fill itself
up" through the leaking seams from the river. It must be added that this was not in the River
Thames. However the danger and the mistrust persist and some shipping companies give instructions
that all water taken from a barge in any port must be chlorinated.
An additional hazard in the transfer of water from shore to ship by water barge is illustrated
by yet another experience in the Port of London. A water barge unable to get alongside an unladen
ship in the optimum position for use of its hose, found that this would not reach tne ship's
filler pipes directly. It was therefore decided to use the ship's deck washing pipe. The pipe was
carefully flushed out first, but it was not realised that this pipe was also the outlet for cooling
water for an auxiliary engine. During the filling operation the engine was started up and a not
inconsiderable pollution resulted. It was fortunately discovered very soon afterwards and no harm
resulted though a lot of cleansing was necessary.
Ship fittings are now generally satisfactory, and conform to the Regulations with the exception
that sight glasses for determining water levels are not often provided. Also the tops of the sounding
pipes which substitute for the sight glasses may be flush with the deck even when the filler
and air pipes are raised. Since tanks in use are normally sounded every day it is a matter worthy
of attention. In this connection it may not be entirely academic to refer to gulls which are proven
carriers of many excretal bacteria, including those of typhoid fever.
Storage. It is from this point on that the supply of fresh water may become needlessly complicated.
The Regulations accept the provision of two supplies of differing quality. One of potable
quality for drinking and cooking purposes and the other, for all other "domestic" purposes. This
second supply need not be fit for drinking. If this system is adopted the two supplies must be
separate at all points. If all fresh water is maintained at potable standard there is no call for
separation. This latter and highly preferable practice is increasing and is now approaching
general application. It should be compulsory. There would then only remain separate fresh water
storage for boilers for which chemical contamination is more important than bacterial pollution.
Tanks for the storage of fresh water can be classed in order of preference —
1. Tanks, other than peak tanks, above the inner bottom, and independent of the hull.
2. Tanks, other than peak tanks, above the inner bottom, but not independent of the hull.
3. Double bottom tanks.
4. Peak tanks.
Classes 1 and 2 are generally recommended for drinking water, but Class 3 is quite acceptable
in cargo liners provided there is no connection with any other water service. Passenger liners
may use any of their tanks, while for whalers in this, as in most other hygienic matters, there
appears to be no specific standards. The reasons for the preference are obvious, but with so
many exemptions it seems doubtful if such a classification serves a useful purpose. It may rightly
discourage the use of peak tanks, which in bad weather, especially the forepeak, are liable to
"pant" and leak at the seams which are also susceptible to impact damage.
The handbook contains numerous other recommendations regarding the siting, internal structure,
drainage arrangements and manholes of tanks. There is an additional Ministry of Transport
Notice advising that drinking water tanks should be opened up, cleansed, cement washed (oi
otherwise recoated) and aired at intervals not exceeding 12 months.
The treatment of water in ships in relation to purification will be the subject of a separate
heading, but reference may be made here to distilled water which, when required to supplement
the fresh water supply for drinking is treated before storage. One such process is to mix 201bs.
of slaked lime and 1½lbs. of stabilised chloride of lime with 100 gallons of fresh water. This is
sufficient to treat 200 tons of distilled water and is fed in before it reaches the storage tank.
This gives a pH of 8.6 and reduces the metal solvency of the water. The water is further treated
in the storage tanks by the addition of a solution of 12 ozs. sodium thiosulphate and 22½lbs. of
sodium bicarbonate in 90 gallons of water. This neutralises the chlorine, improves the palatability,
and gives an alkalinity of 60 mgms/litre pH 7.8.
All tanks in a ship are also concerned with stability and trim. It is thus necessary that
double bottom and peak tanks used for fresh water can be filled with sea water — for ballast — if
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