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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 filling.

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.

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