Supplementary_material

Urban water management faces growing pressure from population growth, pollution, and climate variability, demanding innovative strategies to ensure long-term sustainability. This study applies Life Cycle Sustainability Assessment (LCSA) across four case studies in Brazil and Germany, evaluating integrated systems that combine construct-ed wetlands for greywater treatment with rainwater harvesting for non-potable use. The scenarios include a single-family household, a high-rise residential building, a rural residence, and worker housing. A multi-criteria analysis was conducted to derive consolidated sustainability indicators, and sensitivity analysis explored the influence of dimension weighting. Results show that water reuse scenarios consistently outperform conventional counterparts across environmental, economic, and social dimensions. Life Cycle Assessment (LCA) reveals notable reductions in global warming potential, terrestrial acidification, and eutrophication. Life Cycle Costing (LCC) confirms financial feasibility when externalities are considered, especially in large-scale systems. Social Life Cycle Assessment (S-LCA) highlights perceived benefits in health, safety, and sustainability engagement. Integrated water reuse systems achieved overall sustainability scores up to 4.8 times higher than their baseline equivalents. These findings underscore the effectiveness of decentralized water reuse as a complementary and robust alternative to conventional supply and treatment models, supporting climate resilience and sustainable development goals.