Greywater Reuse: Contaminant Profile, Health Implications, and Sustainable Solutions

Global water scarcity is becoming an increasingly critical issue; greywater reuse presents a promising solution to alleviate pressure on freshwater resources, particularly in arid and water-scarce regions. Greywater typically sourced from household activities such as laundry, bathing, and dishwashing, constitutes a significant portion of domestic wastewater. However, the reuse of greywater raises concerns about the potential risks posed by its complex composition. Despite the growing body of literature on greywater reuse, most studies only focus on specific contaminants, thus there is a limited understanding of the comprehensive profile of contaminants, health, and environmental effects associated with these pollutants. This review adds new knowledge through a holistic exploration of the composition and physico-chemical characteristics of greywater, with a focus on its organic and inorganic pollutants, heavy metals, EDCs, emerging microplastics, nanoparticles, and microbial agents such as bacteria, fungi, viruses, and protozoa. This review sheds light on the current state of knowledge regarding greywater pollutants and their associated risks while highlighting the importance of safe reuse. Additionally, this review highlights the removal of contaminants from greywater and the sustainable use of grey water for addressing water scarcity in affected regions.