Decision aid for water network rehabilitation

The work presented in this paper is carried out within the European project CARE-W (Computer Aided REhabilitation of Water networks. Contract N° EVK1-CT-2000-00053 5th FP), which deals with the development and testing of models and tools for computer aided support of sustainable strategies for water supply network rehabilitation. Three complementary paths to the management of network rehabilitation are followed: the definition of a comprehensive set of performance indicators, the calculation and evaluation of long-term strategic planning, and the prioritisation of projects in the annual rehabilitation plan of a utility according to different objectives. Here, the latter component is presented. The selection of rehabilitation projects requires the consideration of several points of view. A survey among 12 European water utilities revealed the different objectives of rehabilitation and their relative importance, as well as the information that are used for selecting rehabilitation projects. From this inquiry 15 criteria for comparing and evaluating rehabilitation projects were constructed. The criteria are of different nature: they can be cost functions, quantification of observed deficiencies, evaluation of risks, or evaluation of the contribution of a pipe to a problem that occurs in a particular zone. The utilisation of criteria for comparing and prioritising rehab actions is demonstrated.