Water availability is the main limiting factor, both for quantity and quality, of the vegetable production in greenhouses in the province of Almeria. This activity is located in the coastal regions of Campo de Dalías, Bajo Andarax and Campo de Níjar. The water resources of the second zone come mainly from overexploited aquifers with salinity problems. This limits the possible alternative crops, although such restriction could be overcome with the use of desalinated water, available in the region but which has little demand given its higher cost for the farmer. The main objective of this work is to study the profitability of water use in the greenhouse agriculture of Campo de Níjar, analyzing the economic viability of irrigation with desalinated water. So, first a study has been conducted of the cost structure of the most representative alternative crops of the region. Next, the maximum payment capacity for water has been estimated through the apparent productivity of the water, as well as the costs of leveling and closing. Finally, the financial profitability of the crops has been evaluated through the Net Present Value and the Internal Rate of Return. The results show the high average payment capacity for water of this productive system with high levels of financial profitability, which, although very sensitive to the sales prices of the different productions, are not very influenced by the origin and / or cost of irrigation water.