THIS SUPPLEMENT TO VOLUME II (ECONOMIC ASPECTS OF DESALINATION) OF THE DESALINATION MANUAL UPDATES THE MATERIAL OF THAT VOLUME AND REQUIRES REFERENCE TO IT TO BE OF USE. IT PROVIDES NEW GUIDELINES FOR ENVIRONMENTAL CONSIDERATIONS AND ADVANCEMENTS IN DESALTING TECHNOLOGY (ESPECIALLY REVERSE OSMOSIS AND ENHANCED-SURFACE-TRANSFER EQUIPMENT), IT PRESENTS BUDGET COSTING PROCEDURES FOR DESALTING METHODS INCLUDING MULTI-STATE FLASH EVAPORATION, AND IT DISCUSSES THE USE OF BUILDING COST INDEXES FOR KEEPING COST INFORMATION UP TO DATE.