ARCSA: ACC Highland Garage Rainwater Harvest Success Story
TL;DR: Large-scale rainwater harvesting systems, exemplified by commercial buildings, offer significant water savings and can be integrated into new or existing infrastructure.
- Commercial rainwater harvesting offers substantial water savings.
- Systems can be integrated into large infrastructure projects.
- Design considers collection area, rainfall, and storage capacity.
- Re purposing water for toilets and irrigation is effective.
- Compliance with industry standards ensures quality and safety.
- Economic benefits include rapid payback and reduced water bills.
Why it matters: Implementing large-scale rainwater harvesting reduces dependence on municipal water supplies, lowers utility costs, and enhances water resilience, especially in water-stressed regions.
Do this next: Calculate the potential rainwater harvesting capacity for your property based on roof area and local rainfall data.
Recommended for: Property managers, developers, and sustainability officers interested in large-scale water conservation projects.
This document from ARCSA International presents detailed case studies of rainwater harvesting systems implemented in various commercial and institutional settings, emphasizing engineering design, storage capacities, and quantifiable water savings. One key example is the ACC Highland Parking Garage in central Texas, constructed as a new structure with an underground rainwater harvesting system. It features a collection area of approximately 92,000 square feet from the roof, capable of harvesting 1.75 million gallons of rainwater annually based on average regional rainfall. The system captures rooftop runoff and stores it for reuse, demonstrating scalable design for large parking structures in water-stressed areas. Another prominent case is the Eden Prairie Center, designed to ARCSA/ASPE/ANSI Standard 63 standards. Rainwater is collected from a 130,680-square-foot rooftop and stored in four below-ground tanks with a combined capacity of 52,000 gallons. The water is repurposed for toilet flushing and irrigation, saving an estimated 405,840 gallons per year on flushing alone and up to 1.2 million gallons annually for irrigation. This implementation highlights precise sizing calculations tied to catchment area and local precipitation data, along with compliance with industry standards for quality and safety. These cases provide actionable insights for practitioners, including tank sizing formulas (e.g., annual harvest potential calculated as collection area multiplied by rainfall depth and runoff coefficient), integration with building infrastructure, and performance metrics verified through operational data. The studies underscore redundancy in storage to handle variability in rainfall, maintenance protocols for sediment and debris management, and cost-benefit analyses showing rapid payback through reduced municipal water demands. For instance, the parking garage system's design optimizes first-flush diversion implicitly through standard-compliant filtration, reducing contaminants before storage. Overall, these examples offer concrete engineering blueprints, with specifics on tank materials (likely HDPE or concrete for underground use), pump systems for distribution, and monitoring for water quality, making it a high-value resource for designing resilient systems in urban environments facing scarcity.