Smart polymers are artificial intelligent systems that have the remarkable ability to detect and respond to changes in their environment. In the water environment, the design and implementation of smart materials for monitoring pollutant levels in aqueous environments are critical for maintaining the cleanliness and safety of water supplies over time. Water supply systems are consistently vulnerable to a wide range of threats, including natural biological hazards; contamination from chemical sources, including the pharmaceutical and dye industries; and physical alterations caused by dissolved substances. Consequently, diligent monitoring of water quality across various types of water sources is crucial for safeguarding the well-being of humans, animals, and plants. In terms of sustainability, a smart material in the monitoring field must be sensitive, selective, stable, and regenerative. This chapter aims to explore the foundational principles for creating robust smart polymer sensors to monitor crucial water quality parameters, including pH, temperature, ionic strength, heavy metal levels, and organic pollutant contents. The relationships among the structures, properties, mechanisms, and functionalities of smart polymer sensors and their efficacy in monitoring pollutant levels in water should be systematically elucidated, with a focus on current best practices and potential future capabilities.