5.43 TAKING FRESH WATER
In some ports, shore water will have a high mineral content, which
may be detrimental to its use in boilers, but will not affect use as
potable (drinking), water. The primary concern with water taken from
shore is germ or bacterial content. Apparently clear water may contain
typhoid, cholera and other deadly germs. The ship's agent and if necessary
the local consulate office should be questioned regarding the suitability
of using shore water without treatment.
Close attention is required to the mechanics of taking on water. The
hose used for taking water should be reserved for that purpose only.
It should be carefully drained between uses and stored separately in
a clean, dry location with the ends capped. A locked deck box adjacent
to the filling connection is the best storage location. The fresh water
filling connection should be capped when not in use. The hose should
be led onto the dock with its end cap in place and care taken to ensure
that the end of the hose is not allowed to fall into the harbour water.
Water delivery hydrants are often set into wells at the edge of the
berth. If the well contains water, it must be bailed out and the hydrant
thoroughly cleaned. Use a bleach solution for disinfecting the hydrant
connection. Flush the hydrant connection thoroughly before connecting
the ship's filling hose. Flush through the hose after connecting to
the dock but before connecting it to the ship's filling point.
The ship's water tanks must be carefully maintained, including regular
cleaning and reapplication of an approved internal coating or cement
wash. Men assigned to work in the water tanks must be free of disease
and should be clothed in disposable (paper), coveralls, with foot covers,
or freshly cleaned clothing and footwear.
If the water is suspect for drinking purposes, it should be treated
with stabilised chloride of lime in a ratio of 1/250,000 by volume.
This treatment will destroy all organisms in the water within one hour,
leaving no taste or smell. The lime should be added when the tank is
about one-quarter full, so that it will be thoroughly mixed by the subsequent
5.43.1 Non-potable water
Tankers may occasionally take on additional fresh water for purposes
other than crew drinking water. It may be to have a supply of fresh
water for bottom flushing fuel oil from cargo tanks. Fresh water may
also be required for fresh water rinsing cargo tanks after salt water
washing, to avoid salt contamination of the nominated cargo. In this
case, the chief officer must calculate the volumes of fresh water required
and advise the chief engineer of the amounts to be loaded before departure.
Ship's distilling apparatus is normally incapable of processing the
volumes of fresh water needed for cargo tank washing, so enough must
be loaded for the maximum anticipated needs.
If the route of the vessel is one where sea water is not suitable for
processing in the ship's distilling or water-making units, then the
chief engineer will take the additional water in a suitable double bottom,
or afterpeak tank and process it as he would sea water to produce the
necessary boiler or potable water.