Towards Resilient and Carbon-Neutral Philippine Cities: A Systematic Literature Review of Blue-Green Plumbing Infrastructure and Registered Master Plumbers' Role in Climate Resilience and Urban Sustainability
Rapid urbanization, climate-related hazards, and increasing pressure on freshwater resources have intensified concerns regarding the sustainability of urban infrastructure systems in the Philippines. Many cities continue to experience recurring flooding, water supply challenges, inadequate wastewater management, aging utility infrastructure, and fragmented governance arrangements that complicate integrated planning and service delivery. These conditions highlight the need for innovative approaches that can simultaneously improve climate resilience and support low-carbon urban development. This study aimed to examine the potential of Blue-Green Plumbing Infrastructure (BGPI) as a sustainable urban water management strategy and assess its contribution to the development of resilient and carbon-neutral Philippine cities. A Systematic Literature Review (SLR) was conducted using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) framework. Relevant international and Philippine studies were analyzed to evaluate the technical, environmental, institutional, and professional dimensions of BGPI implementation. Particular attention was given to the role of Registered Master Plumbers (RMPs) in the planning, design, operation, maintenance, and regulatory compliance of sustainable water infrastructure systems. The findings demonstrate that BGPI offers multiple environmental and operational benefits. These include improved water conservation, reduced dependence on potable water supplies, lower energy requirements for water treatment and distribution, enhanced stormwater management, increased ecological value, and greater resilience to climate-related risks. The review also indicates that BGPI can support carbon-neutral development by improving water-use efficiency and reducing the energy intensity of urban water systems. However, its broader adoption remains constrained by institutional fragmentation, limited policy integration, financial barriers, insufficient technical standards, and capacity gaps among stakeholders. The study concludes that integrating BGPI into urban planning, building regulations, and water governance frameworks can significantly strengthen urban resilience and sustainability in the Philippines. Achieving wider implementation will require stronger regulatory support, enhanced professional capacity, and greater collaboration among government, industry, and academic institutions.