The efficient use of water and fertiliser is of great importance for vegetable crops in and and semiarid regions. The fertigation solutions developed in temperate areas are not adapted to these conditions, and any modification in composition or concentration affects both water (WUE) and fertiliser (NUE) use efficiencies. The aim of this paper is to evaluate the response of tomato crops in order to optimise the use of water and nutrient input when poor quality water is used in the semi-arid region of south-east Spain. In this experiment, four fertigation strategies were used on a tomato crop (Lycopersicon esculentum) cv. 'Salvador', using water of poor agronomic quality. The experiment was carried out from December 2001 to June 2002 in a cool greenhouse, located in Aguilas Murcia. The substrate used was perlite (0-6 mm) contained in crops channels 20 L plant(-1). Water and fertiliser applications were modified for each different strategy in order to contrast the yield obtained with the input applied. Results show that, from an economic and ecological point of view, the best fertigation strategy consists of reducing fertiliser concentration in nutrient solution by 50%. On the other hand, a reduction of drainage of fertigation volumes applied to less than 20%, can be a good strategy in cool Mediterranean seasons. The different strategies can modify Water and Nutrient efficiencies.