Water sustainability is essential for maintaining a continuous supply of clean water for human consumption, industrial use, and the natural environment. However, human activities have severely contaminated water sources, making clean water increasingly scarce. Present water treatment technologies are often costly, with some producing additional pollutants, driving the need for the development of innovative solutions. One promising approach involves the use of nontoxic, biocompatible polymeric membranes which extract pollutants from water through adsorption. Advances in smart polymeric materials have transformed membrane technology, enabling the development of materials that interact specifically with their environment to achieve purification goals. Smart polymers must be sensitive and selective to targeted contaminants, an attribute that is essential for water sustainability. This chapter highlights the crucial role of smart polymers in ensuring access to clean water, addressing water scarcity, and their applications in purification and monitoring processes. Ultimately, it aims to promote the use of smart polymers as sustainable materials to combat present and future pollution challenges, striving immensely for efficiency in water sustainability.