In a world where one in three people already face water scarcity at least one month a year, continuing to use drinking water for irrigating gardens, washing floors, or filling cisterns is not only inefficient—it is unsustainable. The climate crisis has intensified extreme weather events, bringing torrential rains followed by long droughts in major cities. Yet these rains, far from being harnessed, are often lost through overburdened drainage systems or end up polluting waterways. In this context, the “Rainwater Reuse to Reduce Drinking Water Consumption” project, located in São Paulo, stands out as a visionary and urgent solution that breaks away from the traditional urban water management model.
This rainwater harvesting, storage, and treatment system is installed in public and commercial buildings, significantly reducing demand for potable water in non-potable applications. Every cubic meter captured equals a cubic meter that is not withdrawn from the municipal supply in a metropolis where water stress is already structural. The recovered volume, accurately measured under Method A-3 of the VWBA 2.0 framework, translates into operational resilience, cost savings, and a reduced urban water footprint. By capturing, filtering, and reusing water that was previously lost, the project not only improves water efficiency in the buildings where it is implemented but also helps relieve pressure on the metropolitan reservoirs that supply more than 20 million people.
This initiative emerges in a market where water prices have risen by 38% over the past decade, and where new environmental and fiscal regulations demand real, measurable solutions. Led by Aqua Positive and executed with local technology providers and independent verifiers, the project aligns with the Water Positive strategy by rigorously meeting the principles of additionality, traceability, and intentionality: only the water actually captured and reused is measured, clearly distinguished from usual consumption, and validated through flow sensors and digital records. The result is a scalable, replicable, and commercially attractive solution that transforms urban stormwater management into a new source of value.
The project starts from an opportunity as obvious as it is underused: in São Paulo, more than 1,600 mm of rain fall each year, but less than 2% of that water is harnessed for urban uses. In response to this paradox, a modular rainwater reuse system has been implemented, combining collector roofs, physical filtration, smart storage tanks, and treatment systems using chlorination or UV light, depending on the final application. The solution supplies water for toilets, green area irrigation, cleaning of common areas, and filling of fire protection tanks, all without relying on potable water.
The volume transformed varies by building, but on average, between 800 and 1,200 m³/year are captured per site, generating a cumulative benefit that can exceed 30,000 m³ annually when scaled to the district level. Each cubic meter represents savings of between USD 1.5 and 2, reductions in energy consumption associated with pumping and treatment, and improved adaptive capacity during water restriction periods.
The model has been developed by Aqua Positive in collaboration with local operators, financial structuring partners, and water efficiency experts. Its replicability is assured: it requires no major construction works or structural regulatory changes and can be implemented in public buildings, shopping centers, schools, and companies with ESG targets. Leading companies in sectors such as retail, hospitality, logistics, or technology can adopt this solution as a tangible sustainability flagship, a reputational differentiator, and a means of regulatory compliance.
Acting now is not just an option, it is a competitive advantage. The cities of the future will not be built with more infrastructure alone, but with more water intelligence. This project turns a climate externality, rain, into a strategic asset. It invites every organization to be part of a new urban water economy, where every drop captured is a decision of leadership.
A comprehensive technical solution is proposed that combines advanced systems for capturing, storing, and treating rainwater, along with specific technologies for the effective reuse of treated wastewater in non-essential processes. These solutions meet significant water demands that would normally be met with drinking water, including:
Collection and storage systems with advanced filters and tanks designed to maximize the efficiency and storage capacity of rainwater, ensuring availability during prolonged periods of drought.
Specialized facilities for secondary treatment, including filtration, disinfection, and chemical conditioning processes, guaranteeing high quality standards for reused water in accordance with local and international regulations.
Advanced automation technology and strategically distributed smart sensors constantly monitor the quality and volume of reused water, facilitating real-time adjustments to optimize its efficient use and avoid waste. These integrated systems not only significantly reduce drinking water consumption but also strengthen local water resilience, offering a sustainable and effective solution to the challenges of urban water stress.
SDG 3 – Good Health and Well-being: By ensuring the continuous availability of clean water and reducing pressure on municipal systems, the project contributes to improving sanitary conditions and the overall well-being of the community.
SDG 6 – Clean Water and Sanitation: The project reduces pressure on natural resources, improves sustainable water management, and contributes to the preservation of local aquatic ecosystems, in addition to raising awareness among users about the importance of water.
SDG 11 – Sustainable Cities and Communities: By implementing sustainable and efficient water solutions, the project improves urban resilience to climate change, promoting more sustainable and livable cities.
SDG 12 – Responsible Production and Consumption: The project’s approach encourages the efficient and sustainable use of water, reducing the water footprint and promoting responsible practices in water consumption.
SDG 13 – Climate Action: Reducing drinking water consumption and improving water management mitigate the effects of climate change, increasing the region’s climate resilience.
SDG 15 – Life on Land: Reducing pressure on natural water sources contributes to the conservation of terrestrial ecosystems, helping to maintain their biodiversity and ecological functioning.
SDG 17 – Partnerships for the Goals: The success of this initiative relies on collaboration between government agencies, industries, and environmental organizations. Through multi-stakeholder partnerships, the project fosters knowledge sharing and innovation, ensuring long-term sustainable water management.
The project implementation is structured into several clearly defined stages:
1. Technical Planning and Design: During this phase, specialists will develop a detailed technical project. Specific infrastructure requirements, the required storage capacity (approximately 10,000 m³ per year), the strategic location of rainwater harvesters, and the exact technology for secondary treatment and smart monitoring systems will be clearly defined.
2. Construction and Commissioning: This phase involves the physical installation of all systems. This includes the construction and installation of storage tanks with a minimum capacity of 500 m³ each, collection and distribution networks, advanced treatment systems with an estimated processing capacity of 800 m³ per month, and an integrated network of smart sensors to monitor the system’s operational status in real time.
3. Continuous Monitoring and Auditing: Once operational, a continuous monitoring system will be implemented using approximately 50 strategically distributed sensors to ensure the quality and efficiency of the reused water. Additionally, external audits will be conducted quarterly during the first two years and semiannually in subsequent years, ensuring transparency, effectiveness, and compliance with environmental standards.
4. Training and Communication: Specific training programs will be developed for at least 20 of the mall’s technical staff on the maintenance and management of the implemented system. In parallel, semiannual information campaigns will be launched for mall visitors and employees, with the aim of raising awareness about the importance of water reuse and promoting sustainable water consumption practices.
The project focuses on implementing innovative technologies to address water scarcity by substantially reducing drinking water consumption at Gazit Mall. Using a comprehensive approach that incorporates the capture, storage, and treatment of both rainwater and treated wastewater, the project will generate a significant and sustainable environmental impact.
The implementation of smart sensors and continuous monitoring ensures that the quality and volume of reused water remain optimal, allowing for dynamic adjustments based on the mall’s operational needs. The project’s success will be ensured by independent audits, guaranteeing transparency and reliability of the results obtained.
Additionally, the training of technical staff and ongoing public awareness will reinforce the commitment to responsible water management, establishing a role model for other entities and regions facing similar challenges.
