388 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1961 



Thus the stage is set for an acute shortage of man's most precious 

 commodity. The precariousness of the situation is being augmented, 

 of course, by the increasing population, the many new domestic uses 

 to which water is being put, the rising use of irrigation and industrial 

 water, the pollution of fresh-water streams and rivers, and a general 

 failure to conserve water. 



Very likely the world will get by the present 11-year dry cycle, which 

 is scheduled to merge into a wet decade this year (1961), without too 

 much suffering. And since the wet cycle may iim as much as 7 to 12 

 percent above normal rainfall, the evolution of fresh-water problems 

 from 1962 to 1973 may be somewhat retarded. But beginning with the 

 dry cycle of 1973, when the needs of a much larger population will have 

 to be met, the availability and use of fresh water is expected to take 

 its place among the world's crucial issues — or so the water engineers 

 predict — unless substantial new sources of fresh water are imcovered. 



Education of water users, conservation, and rigidly enforced anti- 

 pollution laws will aid a great deal in alleviating the situation. As- 

 suming, however, that standards of living will not be allowed to slip 

 and that the population will continue to increase, the experts prophesy 

 that nothing offers a permanent solution to future shortages except 

 large new sources of water. This means the conversion of sea water 

 to fresh water. 



Conversion, of course, is nothing new to sailormen who have been 

 doing it aboard ship for many decades. (Large aircraft carriers today 

 convert salt water at a rate of 200,000 gallons per day.) But it is quite 

 another matter to convert salt water to fresh water when the method 

 used must be made to serve the world's millions. 



Progress is being made by a number of methods, mainly through a 

 variety of distillation techniques, solar energy, electrodialysis, and 

 freezing, chemical, and electrical conversion. At present the largest 

 plants converting saline water are located in South Africa, the Persian 

 Gulf, the West Indies, Venezuela, Argentina, Ecuador, Greenland, 

 Italy, and, in the United States, California a,nd Pennsylvania. They 

 convert anywhere from 100,000 gallons per day to 3.5 million gallons 

 per day, at a cost of from $1.74 to $4 per thousand gallons. This 

 compares with American municipal water rates which range from 25 

 to 40 cents per thousand gallons — but which do not reflect the rising 

 costs of developing new sources of fresh water by conventional means. 



When conversion costs drop to around 35 cents per thousand gallons, 

 ocean or bay water will become a major source of the world's fresh- 

 water supply. The Dutch are already operating electrodialysis-mem- 

 brane plants which come close to 50 cents when brackish water (less 

 than a third the salinity of sea water) is used. It is interesting that 

 this is the price paid by Dallas, Tex., residents for a single gallon of 



