The original system provided drinking water to a population of about 33,000, and the total number of consumers was expected to reach 45,000 by the target year of 2015. The principal water source was Río Castán, flowing at a distance of 3.7 km from the city, to its south.

The system was beset by problems, mainly shortage of water during droughts, insufficient conveyance and distribution network capacity, losses through leakage and illegal connections, and inadequate storage volumes.

Work included performance of surface water and groundwater investigations, preparation of an environmental impact study and drawing up of demand forecasts. Based on the findings a rehabilitation plan was proposed, comprising development of two additional surface sources, expansion of the treatment plant, division of the city into more efficient pressure zones, and improvement and enlargement of the distribution network and pumping and water storage systems. An operation and maintenance program was also proposed. The studies were conducted with the help of computerized models developed by TAHAL.

Three alternatives for system development were analyzed and compared and the most favourable one, from the economic and technical viewpoints, was selected.