Using EPANET for modelling water distribution systems with users along the pipes

Traditional hydraulic simulation models (such as EPANET) make it possible to analyse the behaviour of distribution networks by allocating users' water demands to calculation nodes (where pressure head values are calculated by the model). However, water demands are in reality distributed irregularly over the various network pipes and thus their allocation to calculation nodes represents an approximation that may sometimes be unacceptable. This paper shows that these traditional hydraulic simulation models can still be useful in a new approach that takes into account the real distribution of demands along the network pipes; the proposed procedure entails applying the simulation model iteratively, introducing a suitable pipe roughness correction at each iteration in order to represent accurate head losses in the pipes. Application of this approach, based on the use of the EPANET model, to two case studies, and comparison of the results with those yielded by traditional demand allocation schematisations showed that the new approach is more precise in the cases of highly skeletonised networks featuring large pipe water discharge and user demand values while, in the cases of a very detailed description of the pipe network system, use of the traditional or actual demand allocation produces almost the same results.