Rainwater Harvesting Conservation for Old San Juan Buildings

Abstract

This study evaluates the feasibility of implementing a rainwater harvesting system in La Factoria, a commercial historic building in Viejo San Juan, Puerto Rico. The selected multi-story, high-demand facility was used as a representative case study to assess system performance under realistic operating conditions. The motivation for this work arises from recurring water service interruptions that negatively impact business operations and local residents. Monthly precipitation data from NOAA Climate Normals (1991–2020) were used to define rainfall patterns, and hydraulic equations were applied to estimate harvested volume, runoff, storage requirements, and energy demand. Results indicate monthly collection ranging from approximately 6,300 to over 20,000 gallons, with an annual potential of about 170,000 gallons. Pump sizing analysis yielded a required capacity of 0.3–0.5 kW, with low operational cost. These findings confirm that rainwater harvesting is a viable and cost-effective strategy that enhances water resilience and can be scaled across Viejo San Juan for sustainable urban water management.