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The use of adequate decay models for simulating chlorine residuals can effectively aid in chlorine management in water supply systems. In this paper, wall decay in a full-scale water supply system is assessed and modelled using the traditional first-order (FO) model and the recent EXPBIO model. The EXPBIO model was successfully implemented in EPANET-MSX for the first time and predicted chlorine residuals with high accuracy. However, in the tested conditions (chlorine residuals ≥0.55 mg/L and small wall decay rates), the FO and the EXPBIO models described chlorine wall decay with similar accuracy. The results suggest that in systems of large diameter pipes and of high disinfectant concentrations, the simpler FO model can be used for the modelling of chlorine residuals without significant loss of accuracy. Further research is needed to identify in which conditions (chlorine levels, wall decay rates) the EXPBIO model performance may exceed that of the FO model.

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This study compares and discusses the adequacy of surrogate resilience metrics proposed in the literature for resilience assessment of drinking water systems concerning demand increase and network redundancy. A sensitivity analysis is carried out for increasing flow rates using a conceptual case study with different layouts and demand scenarios, selecting several metrics to assess the resilience of two real network areas. Resilience metrics based on surplus energy are sensitive to network layout and demand scenarios. The network resilience index considers hydraulic reliability and network diameter uniformity. In contrast, the weighted resilience index also considers the network topology and gives importance to pipes with higher flow rates. Entropy‐based resilience metrics mainly rely on the network flows' uniformity and are sensitive to pipe redundancy. The entropy metric most adequate to assess the hydraulic capacity is the diameter‐sensitive flow entropy, since it is sensitive to the velocity inside the pipes. Topology metrics cannot assess the hydraulic capacity though evaluate the system redundancy (meshed‐ness coefficient), robustness (central‐point dominance) and water transportation efficiency (average‐path length). Surrogate resilience metrics do not assess the system performance during a failure. They indicate systems which are better prepared to overcome failure events and increased demand events, providing vital information to drinking water systems management.This article is protected by copyright. All rights reserved.