Improving sanitation strategies through coordinated investment on wastewater treatment reuse and water supply at the watershed scale : a brazilian view of water security

Abstract

The discharge of untreated wastewater into water bodies impacts water quality, ecosystems, treatment costs, and water security. Existing investment strategies in water supply and wastewater treatment often lack coordination, particularly among different utilities. This study evaluated the trade-offs between investment costs and economic benefits of sanitation investments in the Jundiaí River Basin, São Paulo State, Brazil. We analyzed economic trade-offs using various investment timelines to achieve different levels of wastewater contaminant removal. Results indicated that delaying investments lowers costs but also postpones and diminishes benefits, such as reduced water treatment costs, energy savings and potential revenue generated by selling water reuse. Postponed sanitation investments show a decreasing benefit/investment ratio, while wastewater treatment and reuse provide significant revenue. These findings underscore the importance of integrating water resources management with sanitation planning to enhance water security and align with circular economy principles. Policymakers should prioritize collaborative frameworks to distribute costs and benefits equitably, ensuring sustainable sanitation practices and contributing to the achievement of Sustainable Development Goals 6.2 and 6.3.