Abstract
Rainwater harvesting (RWH) offers a decentralized option for supplementing conventional water supplies while improving resource efficiency and urban resilience. This study integrates three independently prepared 2026 research projects on rainwater collection and use and places their core observations within a green-economy and policy framework for Azerbaijan. The source projects consistently described a simple system architecture based on roof or surface catchment, gutters and pipes, preliminary filtration, storage, distribution for non-potable uses and, where appropriate, overflow management or groundwater recharge. They emphasized irrigation, cleaning, car washing and toilet flushing as practical applications that can substitute treated freshwater. A structured qualitative synthesis was combined with targeted verification against recent scientific literature and Azerbaijan’s water-policy documents. The analysis indicates that RWH can contribute to resource efficiency through freshwater substitution, local stormwater retention and diversification of water supply. Its economic value, however, is context dependent because installation, storage, pumping, maintenance, rainfall, water tariffs and end-use demand determine financial performance. Azerbaijan’s National Strategy on Efficient Use of Water Resources for 2024–2040 explicitly calls for technical-economic assessment of rainwater collection and a pilot project for its use, strengthening the policy relevance of the approach. RWH should therefore be treated not as a stand-alone solution to water scarcity but as a complementary green-economy instrument that can reduce pressure on centralized water systems and freshwater sources when locally designed, safely operated and economically assessed.