Water scarcity has emerged as a critical global challenge, with India facing acute water stress driven by rapid population growth, industrial development & increase in agricultural field & production, variable rainfall patterns, and unsustainable groundwater exploitation. India accounts for only about 4% of global freshwater resources, resulting in an excessive dependence on groundwater extraction. Conventional water sources such as wells, rivers, ponds, reservoirs are not sufficient to meet the increasing demand for water while increasing urbanization and industrialization has led to degradation and depletion of water quality. This paper discusses the rainwater harvesting potential in District Court buildings of Tezpur, Sonitpur District, Assam by calculating the amount of water that can be collected based on rooftop area, annual rainfall, and runoff efficiency and considering the additional. The results demonstrate that the proposed RWH system can reliably meet a substantial proportion i.e. around 60.16% for average rainfall, 79% for maximum rainfall and 39.2% for minimum rainfall respectively of the building’s non-potable water requirements, particularly for toilet flushing, cleaning, and gardening. The volume of the storage tank is also designed based on demand by considering its length, breadth and height. Overall, the study provides robust empirical and analytical evidence supporting the integration of rooftop rainwater harvesting (RWH) as a practical, scalable, and sustainable solution for meeting potable and non-potable water demands in public buildings and urban environments.

This research evaluated the technical feasibility and performance of a rooftop rainwater harvesting (RWH) system for the district court buildings in Tezpur, Sonitpur, Assam with the objective of offsetting non-potable water demand and promoting sustainable water resource management. The assessment integrated regional rainfall data from last 43 years (1982-2024), effective rooftop catchment area, runoff behaviour, potable and non-potable water demand to estimate the achievable rainwater supply. The study also quantifies the amount of rainwater that can be harvested and effectively utilized within the building. The study concludes that the catchment area yields a total annual harvestable potential of 3117.305 m3 (3117305 litres) for average rainfall, 4095.3048 m3(4095304.8 litres) for maximum rainfall and 2031.136 m3 (2031136 litres) for minimum rainfall. The results demonstrate that the proposed RWH system can reliably meet a substantial proportion i.e. around 60.16% for average rainfall, 79% for maximum rainfall and 39.2% for minimum rainfall respectively of the building’s non-potable water requirements, particularly for toilet flushing, cleaning, and gardening. From a systems perspective, rooftop rainwater harvesting is technically suitable for government office infrastructures and public buildings due to its reliance on existing building components, technical simplicity and scalability of rooftop RWH. Additionally, the findings highlight environmental benefits such as reduced storm water/surface runoff and potential support to groundwater recharge, contributing to broader urban water sustainability goals with principles of integrated urban water management. Overall, the study provides empirical and analytical evidence that confirms effectiveness and integration of rooftop rainwater harvesting that represents a practical, scalable, and sustainable strategy and low-impact engineering intervention capable of supplying a significant fraction of potable water or non-potable water demand in public buildings and urban development.

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