Today unpolluted fresh water can only come from desalination of
seawater, or from treated spring water and rainfall runoff from intact
watersheds.
Most sources are now threatened by increasing domestic demand
and the vagaries of climatic change.
Sea-borne imports and transfers of drinking water are an
attractive option for diversifying water supply in many situations.
Logistic support of military operations and emergency relief
(e.g. following earthquakes, hurricanes and wars such as the Gulf Wars) create further
requirements for transportation of drinking water.
