Achieving Water Neutrality in Turin: Assessing the Potential for Residential Development through Rainwater Harvesting and Water-Efficient Fixtures from Building to City Scale.

Water scarcity is a growing concern, with over 40% of the world’s population living in areas where water demand exceeds supply. Cities must adopt sustainable practices to ensure resource availability for future generations. Achieving water neutrality, where water demand is balanced by water savings, has become a critical objective for urban areas facing population growth and environmental pressures. While numerous methods exist to achieve this balance, from advanced water recycling to greywater systems, residential buildings remain a crucial starting point. This thesis focuses on two key strategies: Rainwater Harvesting Systems (RWH) and the use of water-efficient appliances in existing buildings. The thesis adopts a systematic approach to evaluate how RWH and efficient appliances can contribute to water savings in Turin's residential sector. By retrofitting existing residential buildings, water savings can be redirected to supply the demand of new developments, thus preventing the need for increased water extraction from natural sources. RWH systems collect and store rainwater for non-potable domestic uses, such as toilet flushing and laundry, while water-efficient appliances reduce potable water consumption. The study employs the Representative Building method, analyzing different building typologies across Turin’s neighborhoods. The results demonstrate that water neutrality potential varies significantly depending on building type and location. For instance, in districts like Crocetta and Centro, the water savings from retrofitted buildings (Building Typology 1) can supply more than one new building of Typology 6 in hilly areas, where water demand is significantly lower. However, achieving water neutrality is not uniform across all neighborhoods. In areas with higher water demand, such as the city center, bigger efforts are needed, and strategies that overcome the building’s barriers, such as BGI and Social awareness campaigns must be implemented, to meet the water neutrality goal, and improve the residential development potential. While significant progress toward water neutrality is possible with current technologies, further research is needed to explore the integration of smart systems and emerging water-saving innovations. Additionally, future studies should analyze water demand variability across seasons and develop region-specific strategies to enhance water efficiency and achieve water neutrality in urban settings.