This paper consists of a theoretical analysis, in terms of water transport costs, tariffs, return on resources and social welfare, of three criteria applicable to the planning of interbasin transfer. The criteria studied are the minimization of water transport costs, the fixing of water tariffs equal to average transport cosis and the fixing of socially optimal ta-riffs. In order to illustrate the theoretical analysis, a simulation has been carried out based on available data on national water resources and its distribution wilhin geographical basins, as well as estimations of demand prior to the Hydrologic Plan ("Plan Hidrológico"). This simulation allows us to evaluate the social cost of applying non-optimal criteria.