264 THE FUTURE OF ARID LANDS 
govern the choice between fresh and saline supplies. Untreated 
or partially desalted saline water must be utilized where and when 
possible to limit consumption of costly demineralized water, thus 
minimizing the overall water cost to consumers. 
Presently available unit costs of demineralized water from 
various processes are based upon laboratory research and small- 
scale pilot plant operations, and should be considered only 
approximations of ultimate costs. These costs may change con- 
siderably in large-scale operations. Research data are invaluable, 
however, for comparing cost of various desalting processes under 
specific regional conditions, but may not be broadly applicable 
except where comparable conditions are known to exist. Accept- 
able costs for desalted water for military operations in areas 
wholly devoid of fresh water, or where fresh water is in short 
supply, would be prohibitive in areas where water from this source 
is in competition with imported water or where reuse of existing 
local water 1s practicable. 
Little effort has been made, individually or collectively, to 
grade quantity and quality of water for man’s specific require- 
ments. Intelligent planning and wise use of salt and fresh water 
would, we believe, produce results fully commensurate with the 
effort and cost involved. 
At the beginning of the Saline Water Conversion Program, the 
cost of converting sea water to fresh water by the best known 
process was estimated at $400 to $500 per acre-foot. For economic 
evaluation of demineralization processes, two arbitrary cost goals 
were set, one for municipal water and one for irrigation water. 
These goals were $125 and $40 per acre-foot, respectively (38 and 
12 cents per 1,000 gallons). For these criteria, no distinction is 
made between sea water and brackish water as the supplies to be 
converted: (rma): 
No process has been developed up to the present time which 
has met the desired initial cost goals. In fact, all schemes proposed 
or in actual pilot-plant or full-scale production now show costs 
in excess of these criteria. However, the results of current research 
indicate that the goal of producing fresh water at a cost which 
municipal and industrial consumers can pay seems to be in sight. 
