Abstract

Water scarcity poses a critical challenge to sustainable development in the context of increasing demand, climate change, and limited infrastructure. In Chile, where over 70% of the territory is affected by drought, decentralized water reuse strategies alleviate pressure on freshwater supplies. This study explored a resource-efficient approach to greywater reuse by segregating laundry greywater by its different washing machine cycle stages (wash, rinse, spin) to minimize treatment requirements and optimize reuse potential. Greywater samples were collected from domestic washing machines and analysed for turbidity, total suspended solids, chemical oxygen demand, faecal coliforms and residual chlorine. Results confirmed that the rinse and spin stages consistently exhibited lower pollutant concentrations than the wash stage, often complying with regulatory standards for ornamental and subsurface irrigation without requiring treatment. In contrast, wash-stage greywater contained higher loads of surfactants and particulates, requiring further treatment. Two filtration systems, simple gravity-driven sand filters, made up of two and three-layered arrangements, were tested at lab scale. The three-layered system, which included silica sand, achieved up to 94% turbidity and 86% total suspended solids removal, enabling compliance with Chilean greywater reuse regulations. Statistical analysis confirmed significant differences in performance between configurations, highlighting the added value of optimized media layering. By reducing the volume of greywater requiring treatment and enabling selective reuse, stage-based segregation represents a scalable, low-cost strategy for improving water recovery in drought-prone regions. The findings support the design of decentralized greywater systems with minimized operational complexity, offering a practical contribution to water management in resource-constrained environments. © The Author(s), under exclusive licence to Springer Nature Switzerland AG 2025.