The climate crisis and urban pressure have placed water at the center of the greatest challenges of this century. In São Paulo, a megacity with more than 20 million people, the memory of the 2013–2015 water crisis still persists as proof of the fragility of its supply systems. Every dry summer intensifies the risks: polluted rivers, overexploited aquifers, and increasing dependence on uncertain sources. In this context, the Brazilian water market shows alarming figures: more than 35% of distributed water is lost in leaks and irregular connections, while the rate of urban reuse does not exceed 2%. This scenario highlights the urgency of innovative projects that change the linear consumption logic toward regenerative and circular solutions.
The current urban commercial market reveals intensive and inefficient consumption, with shopping centers almost entirely dependent on public supply to cover both potable and non-potable needs. The raison d’être of this project is to respond to that structural deficit, reducing pressure on the public network and demonstrating that a large building can become a hub of efficiency and water resilience.
This site rises as a pioneer of this transition. With the installation of a Wastewater Treatment and Reuse Plant (EPAR), with a capacity of 8.3 m³/h (approximately 6,000 m³ per month), its discharges are transformed into an alternative source of supply. More than 3,200 m³ per month are reused in cooling towers, restrooms, and cleaning, achieving an annual benefit of about 39,000 m³, equivalent to the consumption of more than 200 Brazilian households. The strategic objective is unequivocal: to transform an environmental liability into a circular and reliable solution. Traceability and external validation, under the VWBA 2.0 methodology, ensure that the benefit is additional, intentional, and verifiable.
Key actors in this initiative include the site operator, the technology provider responsible for investment and operation, and regulatory authorities ensuring compliance. This alliance demonstrates how the private sector can lead the Water Positive agenda and create replicable models at the urban scale. Beyond efficiency, this project opens the door to a transformative narrative: every drop reused becomes a strategic asset for the future of cities.
The challenge stems from a stark reality: São Paulo’s urban water supply system is under enormous pressure, with degraded surface sources and overexploited aquifers. Large consumers, such as shopping centers, exacerbate this tension by depending on potable water for non-essential uses such as restrooms or cooling. This practice is not only inefficient but unsustainable in the context of growing water stress and regulatory risk. The problem is aggravated by structural causes such as the lack of specific regulations for large-scale reuse, delays in modernizing distribution networks, and a consumption culture that still privileges potable water even for secondary purposes.
The opportunity lies in using the effluents generated onsite, treating them with an advanced system that combines grease traps, screening, MBBR biological reactor, secondary clarification, sand and activated carbon filtration, and chemical disinfection. This generates a stable flow of safe water for onsite reuse. The immediate impact is a 50% reduction in volume purchased from the public utility and groundwater extraction, achieving an annual saving of almost 39,000 m³. In the short term, this decreases the site’s water footprint; in the medium term, it reduces operating costs and dependence on the network; in the long term, it strengthens urban resilience against droughts and enhances social license to operate.
The expected benefits are multidimensional: operational efficiency and savings, regulatory compliance, resilience against water crises, and reputational positioning in sustainability. The project model allows replication in other commercial centers, industries, or urban complexes, consolidating a multiplier effect across the city. For companies with ESG commitments and water neutrality goals, this intervention represents a tangible case of how to transform risks into opportunities, comply with emerging regulations, and strengthen corporate reputation. Acting now is not only strategic: it is imperative in a market that demands circular, measurable, and visible solutions.
The technical solution is based on a hybrid physical-biological-chemical process designed to ensure the quality and stability of the regenerated water. Alternatives such as purely biological systems or MBR membranes were considered; however, the MBBR scheme with filtration and disinfection was chosen for its optimal balance of cost, operational efficiency, and ease of maintenance in a complex urban environment. The nominal capacity of 8.3 m³/h (about 6,000 m³ per month) guarantees constant supply for restrooms, cooling towers, and cleaning.
The technical justification rests on criteria of water efficiency, replicability, and regulatory compliance. This approach solves the problem of discharges without value, converting them into a useful resource, and aligns with Water Positive and VWBA principles (intentionality, additionality, and traceability). This option was prioritized for its integration with existing systems, lower energy footprint, and ability to guarantee external audits.
The expected benefits are multiple: saving 39,000 m³ of potable water annually, reducing discharges to the sewer system, and complying with ABNT NBR 16783:2019 and GM/MS Nº 888/2021. Environmentally, it lowers pressure on rivers and aquifers and reduces the carbon footprint associated with external pumping and treatment. Socially, it ensures service continuity even during droughts, contributes to public health by preventing contamination, and strengthens the site’s social license. Economically, it means lower supply costs, operational resilience, and enhanced ESG reputation.
Identified risks include technological failures, variability of effluent load, user resistance, or regulatory changes. To mitigate them, redundant systems, online monitoring with IoT sensors, contingency plans, shared governance protocols, and continuous staff training are implemented. Climate resilience is reinforced with additional storage capacity and a preventive and predictive maintenance plan. Finally, the solution has high scalability potential to other commercial complexes, hospitals, or corporate buildings, provided clear regulatory frameworks and public-private partnerships are in place.
The project follows a phased and technically robust approach.
In the first stage, a comprehensive diagnosis of water consumption and effluent generation was carried out. This included hydraulic balances of all supply points, characterization of average and peak flows, and detailed laboratory analyses of effluent quality (BOD, COD, TSS, oils and greases, nutrients, and coliforms). This established the baseline of approximately 6,000 m³/month of effluent available for treatment and reuse.
In the second stage, the treatment plant was designed in full compliance with ABNT NBR 16783 and GM/MS Nº 888/2021. Hydraulic and biological simulations were conducted to size the MBBR reactor, clarify optimal retention times, and determine filtration surface areas and disinfection requirements. Operation diagrams, redundancy systems, and control instrumentation were also defined.
In the third stage, infrastructure was built and installed, including equalization tanks, grease traps, the MBBR reactor with media carriers, secondary clarifiers, pressure sand and activated carbon filters, and chemical disinfection units. Electrical panels, SCADA integration, and safety systems were incorporated. The execution period was about six months, including civil works and electromechanical assembly.
In the fourth stage, commissioning and validation were carried out. Hydraulic testing, calibration of flowmeters and sensors, and laboratory analyses confirmed compliance with legal and reuse standards. IoT sensors connected to the SCADA system generated real-time reports, enabling comparison of with- and without-project scenarios and quantification of volumetric water benefits (VWB).
The final stage corresponds to continuous operation, ensuring the permanence of benefits over time with protocols for adaptive management and process optimization.
During operation, physical traceability is guaranteed through inline flowmeters at influent and effluent points, while digital traceability is ensured by the SCADA system with cloud storage and secure access. Automatic alarms flag deviations and activate immediate response protocols. Key Performance Indicators (KPIs) include total volume treated, volume reused onsite, water quality parameters (BOD, COD, TSS, coliforms), and cubic meters saved compared to the baseline. External validation will be conducted through annual third-party audits, calibration of instruments, and independent verifiers to comply with VWBA/WQBA frameworks.
The maintenance plan includes weekly preventive routines (cleaning of screens, calibration of sensors), monthly inspections of mechanical and electrical components, and immediate corrective actions. Predictive maintenance will be supported by vibration analysis of pumps and energy consumption monitoring. Governance is organized with the technical operator responsible for O&M, the site management as the beneficiary, and regulatory authorities as compliance verifiers. Continuous improvement is ensured through real-time data feedback, annual protocol reviews, periodic technological upgrades, and benchmarking against best practices, guaranteeing that volumetric and quality water benefits are sustained over time.
The water reuse project consists of installing and operating a Wastewater Treatment and Reuse Plant with a capacity of 8.3 m³/h. The technical process integrates pretreatment, MBBR biological reactor, clarification, sand and carbon filtration, and chemical disinfection. The regenerated water is used in restrooms, cooling towers, and cleaning, reducing potable water dependency by 50%. It complies with ABNT NBR 16783:2019 and GM/MS Nº 888/2021, ensuring safety for non-potable uses.
The relevance lies in addressing São Paulo’s urban water challenge, where demand grows faster than supply and stress is recurrent. Before the project, all effluent was discharged without use, representing a constant loss. With the intervention, discharges are converted into a reliable circular supply source, reducing pressure on the public network and aquifers.
Concrete results include saving 39,000 m³ of potable water annually, lowering discharges, and delivering environmental benefits such as reduced stress on rivers and aquifers; social benefits by reinforcing urban water security; and economic benefits through reduced supply and treatment costs. Strategically, it aligns with the Water Positive roadmap, offering ESG credentials, competitive differentiation, and regulatory compliance. It also fulfills VWBA principles of intentionality, additionality, and traceability, ensuring physical and digital validation of benefits.
The model is replicable in commercial centers, hospitals, and corporate buildings across Brazil and other water-stressed cities, provided regulatory frameworks and investment willingness exist. Public-private and technology partnerships facilitate expansion and scalability.
In summary, the final impact is a positive water balance for the urban basin, greater climate resilience, strengthened social license to operate, and a clear message to the market: it is possible and necessary to transform how we manage water in cities.
