Waste water treatment through public-private partnerships: The experience of the regional government of Aragon (Spain)

This paper analyses the experience of the regional government of Aragon (Spain) that has extensively used public-private partnerships for the construction and operation of waste water treatment plants. The paper argues that although overall the implementation of this PPP program might be considered successful, most projects have experienced significant difficulties and long delays until they have entered in operation. The analysis shows that the main reasons for the problems in the implementation of the program were the rush in implementing it, the inadequate transfer of some risks, and the wrong allocation of some tasks. The paper also illustrates two features of this PPP program that arguably have strongly influenced its successful implementation: The mitigation of demand risk and the rigorous estimations of demand carried out by the regional government