In this thesis, the first investigation into reclaimed water was on lemon trees (Chapter II). The aim of this work was to study the effects of reclaimed water on lemon tree performance. This research was to compare two sources of treated wastewater, one obtained with a secondary treatment (Cartagena) and the other with a tertiary treatment blending with well water (Campotejar), and to study their effects on soil chemical properties, on the leaf mineral status, crop production and fruit quality and safety.The main objectives of the second study were to evaluate the combined effects of different irrigation water qualities and the regulated deficit irrigation strategies on mandarin tree crop under Mediterranean climate and their effects on plant physiology and leaf mineral status, soil chemical properties and water content, yield and fruit quality (Chapter III). The last work was based in the use of Geographical Information Systems (GIS) as a tool in the planning and management of water reuse projects (Chapter IV). The work was developed with the aims at identifying potential sites for reclaimed water use, using a GIS- based multi-criteria analysis.