Water scarcity is a characteristic of north-western states of India, such as Gujarat. Over time, the continuous increase of the population as well as the financial, administrative and technical deficiencies of the new supply system have lead to the deterioration of the water service in the city. In the meantime, the water demand has considerably increased due to the improvement of standards of living. This has resulted in an increasing pressure on underground water resources, which has lead to an alarming depletion of aquifers. From this overall situation arises the question of the use of complementary alternative sources of water in Ahmedabad and more particularly of the rehabilitation of the rainwater harvesting structures still existing in its old city area. The objective of the research is to evaluate to what extent this traditional system may constitute an additional source of water within the Old city of Ahmedabad and may locally reduce the pressure on water demand, assuming that the existing supply system does not fulfil the needs of the users. The results of an exploratory field study conducted in the Old city in 2001-02, which combined quantitative and qualitative aspects, give an outlook on people's opinions and behaviors regarding both systems. Finally, the rehabilitation of rainwater harvesting structures in the Old city of Ahmedabad suggests the necessity of empowering local structures of water management (households, non governmental association) in semi-arid urban areas to create the conditions for a sustainable implementation.