<p>The growing scarcity of freshwater presents a serious challenge to sustainable urban development, especially in low-income communities where access to safe water remains limited. Greywater reuse provides a practical and sustainable way to supplement domestic water supplies due to its constant availability and low organic load. This review critically examines the properties of greywater and assesses the effectiveness of eco-friendly, low-cost treatment technologies like constructed wetlands, bio-sand filters, membrane bioreactors, and photocatalytic systems. Comparative analyses of regulatory frameworks in Israel and Australia offer insights into effective policies that could guide greywater management in developing countries. Additionally, the review includes economic evaluations, risk assessments, and public engagement strategies to provide a comprehensive understanding of the technical, financial, and social aspects influencing greywater reuse. The findings indicate that constructed wetlands and bio-sand filters are the most practical options for low-income urban households, while advanced systems such as photocatalysis and MBRs face challenges related to cost and scalability. The paper emphasizes the importance of localized policy support, community education, and innovative hybrid systems to improve long-term sustainability. Overall, this study offers a comprehensive framework connecting technology performance, economic factors, and societal acceptance, while highlighting key research areas for achieving Sustainable Development Goal 6 (Clean Water and Sanitation) through decentralized, context-specific greywater management.</p>