Abstract
The Isolation Valve System (IVS) allows to detach some portions of water distribution networks (WDN) to perform planned (e.g. maintenance) or unplanned (e.g. failures) works. Isolating WDN segments causes pressure reduction and possible insufficient water supply conditions; the larger the number of valves (and segments) the larger the reliability of the system in face of segment isolation scenario. This contribution introduces some reliability indicators ranging from single node and time step up to the entire WDN, based on the explicit pressure-driven hydraulic simulation of the system under each segment isolation scenario over an operating cycle. Such mechanical reliability indicators are used to support the selection among optimal alternative IVS design solution obtained by minimizing the number of valves and the length of segments. The strategy is demonstrated on the real WDN serving the municipality of Oppegård (Norway).