Abstract for: Understanding Low Tap Water Intake and SSB Substitution in Puerto Rico: A Work in Progress System Dynamics Model

Tap water consumption in Puerto Rico remains low while sugar-sweetened beverage (SSB) intake is high, particularly among households with young children. Concerns about water quality, infrastructure, and contamination shape trust and influence behavior. These factors interact through reinforcing feedbacks, making it difficult to shift consumption toward healthier patterns over time. We translated a participatory causal loop diagram developed through group model building into a stock-and-flow model. The model focuses on interactions between perceived contamination, trust in water quality, and beverage choice. Survey data collected in Puerto Rico are used to estimate initial conditions and inform parameters governing trust dynamics and substitution between tap water and SSB intake. An initial stock-and-flow model has been developed linking infrastructure conditions, perceived contamination, trust, and beverage consumption. Survey data collection is complete, and preliminary calibration is underway. Early model structure reproduces the hypothesized direction of relationships, with declining trust associated with reduced tap water intake and increased SSB consumption, though full validation has not yet been conducted. This work demonstrates how participatory system maps can be translated into simulation models that capture perception-driven behavior. By focusing on trust as a dynamic component, the model highlights potential leverage points for intervention. Ongoing work will refine parameterization, expand system boundaries, and test policy scenarios to better understand how to shift consumption toward healthier alternatives.