Exploring Vulnerable Nodes, Impactful Viral Intrusion Sites, and Viral Infection Risk Reductions Offered by Chlorine Boosters in Municipal Drinking Water Networks

The effects of drinking water system infrastructure on water quality and health following intrusion events have not been extensively studied. This study proposes a coupling of hydraulic and water-quality modeling with quantitative microbial risk assessment (QMRA) to characterize microbial infection risks. Two networks were considered based on their network configuration. We assumed a continuous intrusion of enterovirus under three scenarios. The location of vulnerable and influential nodes in a looped and a branched network were compared, followed by a comparison of chlorine booster placement to reduce infection risks. The most vulnerable nodes in the branched network were generally downstream of the intrusion site, whereas those for the looped network were in the middle of the network due to tank dynamics. Influential injection nodes for the looped network were also in the middle of the network but mostly located at the upstream nodes for the branched network. A single chlorine booster yielded a risk reduction (47.6%) for the branched network, greater than for the looped network (nearly none). Two chlorine boosters reduced the looped network risks more notably (63%). The generalizability of these results to other networks likely depends upon specific network hydraulics and variability in municipal drinking water use. This work will help public water system managers in identifying vulnerable points in their distribution system and optimal locations for risk reduction strategy implementation.