This chapter delves into the pressing issues surrounding water purification, emphasizing the importance of addressing common contaminants and developing sustainable solutions. It critically examines the shortcomings of conventional purification methods and introduces green nanotechnology as a promising alternative to overcome these limitations. The focus is on biopolymer-based nanomaterials, which are explored in detail, including their various types and applications in water treatment. The chapter highlights the eco-friendly nature of these materials and their efficacy in removing contaminants from water sources. A comprehensive analysis of the environmental impact and safety considerations associated with green nanotechnology is presented, providing a balanced perspective on both the advantages and potential risks of this innovative approach. In addition, the chapter describes the synergistic potential of combining green nanotechnology with other emerging water treatment technologies, such as advanced membrane nanofiltration, photocatalysis and biologically mediated processes. It explores how these integrated approaches can lead to more comprehensive and efficient water purification solutions, capable of addressing a broader spectrum of water quality issues. The chapter concludes by outlining future research directions and anticipated challenges in the field, emphasizing the significant role that green nanotechnology is expected to play in advancing global water purification efforts. By addressing these crucial aspects, the chapter underscores the potential of this technology to contribute to more sustainable and effective water treatment solutions, ultimately supporting global efforts to ensure access to clean and safe water resources.