With the rise in water pollution, the need for advanced materials for sustainable water treatment has become a critical goal. In this context, polymers have emerged as versatile materials for water purification and treatment due to their numerous advantages in terms of material properties and application technologies. The chapter begins with an overview of the current global water crisis and the need for innovative solutions for water remediation using cutting-edge materials. This chapter further delves into the various types of polymers and their use in water treatment, including natural, synthetic, and hybrid polymers, highlighting their unique properties and current applications. The chapter subsequently describes the use of polymers in different types of treatment technology for water contamination removal, such as polymeric adsorbents, nanomaterials, membranes, and hydrogels. Methodologically, the chapter reviews recent literature and case studies to provide a comprehensive analysis of polymer-based water purification systems. It discusses detailed processes and mechanisms through which polymers remove contaminants, such as adsorption, electrostatic attraction, diffusion, covalent bond formation, flocculation, and ion exchange, through their active functional groups and physicochemical interactions. Special emphasis is given to the synthesis and functionalization of polymers to increase their efficiency and selectivity in targeting specific water pollutants. The key content includes an assessment of innovative polymeric materials such as nanocomposites, hydrogels, and membranes and hybrid systems for water purification. The chapter concludes with future directions and potential developments in the field of the use of polymeric materials in water treatment, offering insights into ongoing research and emerging trends.