In this study, part of the SEE URBAN WATER team analyzes the technical potential and feasibility to upscale subsurface flow constructed wetlands for decentralized treatment of domestic greywater. An urban watershed in the Greater Metropolitan Area of Costa Rica was stablished as a case study area to develop the research. Using GIS tools, the quantity of greywater being discharged to the river, given the current situation, is estimated for the whole catchment area. A spatial analysis of the watershed was carried out to identify potential areas for the implementation of this type of NbS for on-site greywater treatment. Based on this analysis, a scenario for the treatment of greywater before discharge to the river is created. Taking account of the suitable areas for the implementation of this NbS along the watershed, an estimation of pollutants’ reduction by virtue of the treatment is calculated, based on removal efficiencies reported in literature. The results contribute to the discussion and understanding of the potentiality of NbS to improve the environmental quality of surface water resources, not only in Costa Rica, but also other areas in the region where similar sanitation schemes prevail.
