The Philippines is known to have abundant rainfall averaging from 960 to 4000 mm annually. Despite this abundance, water scarcity is imminent and growing especially during the dry periods. Despite its archipelagic structure and abundance in rainfall, the Philippines is projected to be water stressed in 2040. The need for alternative and intermittent water sources such as rainwater harvesting rises. Rainwater harvesting (RWH) is defined as the collection, conveyance, storage, and treatment of rainwater for on-site use. Currently, there is limited research on rainwater harvesting application in the Philippines and there is no established standard or guidelines for its local design, construction, operation, and maintenance. This study reviews rainwater harvesting, its history, its components (catchment, conveyance, first-flush diverter, storage), harvested rainwater quality, and treatment methods for possible nation-wide adoption in the Philippines. Some problems hindering the integration and implementation of this technology include lack of acceptance, motivation, and involvement among potential users, missing hydrological data and information for confident planning, design, and implementation of RWH systems, and insufficient attention to social and economic aspects such as land tenure and unemployment. To address these, possible strategies to encourage implementation of RWH include information education campaign strategies to promote the value and latest development of the technology, offering subsidy and interest loans for potential users, tax exemptions for private institutions, and strict implementation, review, and expansion of RA 6716, “An Act Providing for the Construction of Water Wells, Rainwater Collectors, Development of Springs and Rehabilitation of Existing Waterwells in All Barangays in the Philippines” for government institutions. With the advancement of technology, GIS-based decision making can be implemented in optimizing the location and sizing of rainwater harvesting systems.

Topics
Hydrology, Education, Careers and professions, Public policy and governance, Review
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