Management of water networks. Proceedings of the Conference "Efficient Management of Water Networks. Design and Rehabilitation Techniques". Ferrara, May 2006

Also in the light of recent legislation on the subject (law 36/1994 for instance), the design of water distribution systems is moving towards new approaches which, beyond the traditional sizing of the principle components, allow for explicit consideration of the degree of effectiveness and efficiency that the system is able to guarantee. An objective measure of effectiveness is reliability, which can be defined as the probability that the system will fulfil - under specific conditions and durations - the functions for which it has been designed. The reliability of a system can be quantified through an evaluation of the nodal and global indices with long-term simulations, in which the time variations of the pipe failure rates, of the uncertain nature of the water demand and of the pipe roughness can easily be included. As regards the second parameter (efficiency), it is evident that we need a thorough knowledge of the leakages estimated as the ratio between the quantity of water delivered and that supplied to the network. The rehabilitation of the water distribution systems and, more generally, their proper and careful management allow the highest global performances to be obtained from these systems, as demonstrated by some case studies collected in these Proceedings, in which equal importance is given to the distribution service and to the reduction of water wastage.