ASSESSING RAINWATER HARVESTING OPTIONS IN TERESA, RIZAL: INCORPORATING USER PREFERENCES WITH MULTI-CRITERIA DECISION ANALYSIS

Abstract

Water scarcity has emerged as a critical global challenge, necessitating the exploration of alternative water sources. Rainwater harvesting (RWH) presents a promising solution, given its abundance and ease of collection. Despite the Philippines' ample rainfall, RWH remains underutilized, capturing merely 6% of the annual precipitation. To bolster RWH adoption, this study aims to investigate residents' preferences for alternative water systems, with a specific focus on cost-effectiveness and reliability. By addressing these factors, we aim to identify key strategies for promoting and implementing RWH to mitigate water scarcity and foster sustainable water management practices in the Philippines. Preferences of rural residents (n = 185) in Teresa, Rizal on RWH alternative was then evaluated using a multi-criteria decision analysis. The main criteria assessed were reliability, cost, adoption factors, and benefits. The analysis involved assessing and converting the scores into Yield After Spillage (YAS) to establish rainfall reliability. The study employed Multi-criteria Decision Analysis (MCDA) to compare and evaluate various alternatives based on different factors, which were subsequently ranked under different scenarios. The study found that Alternative P10, a 1,000L plastic tank with a 20L first flush, exhibited the highest utility score among the assessed alternatives, with a score of 0.617. Notably, Alternative F30, featuring a 3,000L ferrocement tank with a 200L first flush, closely followed with a utility score of 0.614. The study employed the Jonckheere-Terpstra test and Kendall's tau with a significance level of 0.05 to determine the significance of these criteria concerning increasing income. The criteria of price, maintenance, and durability were identified as statistically significant (p-values: 0.007, 0.031, and 0.005, respectively) as residents' income increased. Consequently, residents with higher incomes placed greater importance on Alternative F50, a 5,000L ferrocement tank, due to its alignment with these influential criteria. Moreover, given the potential impacts of changing rainfall patterns and growing water demands, implementing larger storage tanks, like Alternative F50, is advisable to enhance future water sustainability in Teresa, Rizal.