Challenges in Mathematical Modelling of Anti-Microbial Resistance Fate in Water Systems

<p dir="ltr">Antimicrobial resistance (AMR) is a growing global health threat, with engineered water systems, especially drinking water, and reclaimed water, emerging as potential reservoirs and transmission pathways for antimicrobial-resistant bacteria (ARB) and genes (ARGs). Biofilms within these systems provide long-term refuge for resistant microbes and facilitate horizontal gene transfer, while their complex structure shields microorganisms from disinfectants. The lack of standardized monitoring and limited data further complicate efforts to model and mitigate AMR spread through water infrastructure. Mathematical modelling is a critical tool for understanding AMR dynamics in water systems. However, developing accurate models remains challenging due to the need to represent multiscale biological and chemical processes within operational hydraulic systems. Balancing model complexity, data availability, and computational feasibility is a persistent obstacle. In this study, we develop a simplified but comprehensive mechanistic model for AMR fate in chlorinated reclaimed water storage tanks, key component in water reuse schemes, particularly for agriculture during peak demand. The model captures key interactions between chlorine decay, microbial regrowth, and AMR persistence in both bulk and biofilm phases. This work represents a step toward integrating AMR considerations into routine water quality modelling. By focusing on modular based modelling approach reclaimed water systems, we provide a scalable foundation that can be extended to drinking water networks.</p><p dir="ltr">This paper was presented at the 21st Computing and Control in the Water Industry Conference (CCWI 2025) at the University of Sheffield (1st - 3rd September 2025).</p>