Comparative Life Cycle Assessment of Different Rainwater Collection Systems in Philippine Public Schools

Rainwater Collection System (RWCS) is a sustainable water management technology suitable for the collection and storage of rainwater from roofs and surfaces for reuse to promote sustainable water resource management. This study investigated four RWCSs to be used in public schools across the Philippines. These RWCSs are: (1) Aboveground Steel Tank (A-S), (2) Aboveground Polyethylene Tank (A-P), (3) Underground Reinforced Concrete Tank (U-C), and (4) Underground Polyethylene Tank (U-P). Life Cycle Assessment was utilized to consider the environmental performance of four RWCSs with the use of SimaPro (10.5.0.1). A cradle-to-site system boundary was adopted encompassing two life cycle stages: manufacturing and installation. The results showed that the Underground Concrete Tank system (U-C) consistently exhibited the lowest environmental impact across all impact categories, and the Aboveground Steel Tank system (A-S) demonstrated the highest impacts, primarily due to the significant use of reinforcing and structural steel for its base and foundation. In particular, the global warming potential (GWP) and human carcinogenic toxicity (HCT) of U-C are lower than those of the other RWCSs from 47.3% to 59.4% and 44.1% to 93.3%, respectively. In addition, the construction cost of U-C is 20.4% to 35.1% lower than that of the other RWCSs. Future research is recommended to expand the system boundary to include use and end-of-life stages, which may influence the comparative outcomes.