Water is one of the most essential natural resources for sustaining life; however, its contamination by industrial, agricultural, and domestic wastes has become one of the major environmental challenges of the modern era. In this context, chemistry plays a fundamental role in developing effective methods and technologies for water treatment, making water safe for human use and environmental sustainability. Water treatment relies on chemical principles aimed at removing various contaminants such as suspended solids, organic compounds, heavy metals, excess salts, and harmful microorganisms. These processes include coagulation and flocculation, in which chemical agents such as alum and ferric chloride are used to aggregate and precipitate suspended particles, facilitating their removal through filtration. Chemistry also plays a crucial role in water disinfection processes. Chlorine and its compounds, ozone, and hydrogen peroxide are commonly used to eliminate pathogenic microorganisms and ensure the safety of drinking water. In addition, chemical techniques are applied to control water pH levels and prevent corrosion in water distribution systems. In wastewater treatment, chemistry contributes significantly to the degradation and removal of pollutants through advanced chemical processes such as oxidation–reduction reactions, ion exchange, and chemical precipitation. These methods reduce environmental pollution and help conserve water resources. Furthermore, green chemistry has led to the development of environmentally friendly treatment materials and techniques that minimize the use of hazardous chemicals. In conclusion, chemistry is a key pillar in water treatment and protection from pollution. It ensures the availability of safe and clean water and supports sustainable development by preserving this vital resource for future generations. Al-Mustaqbal University Ranked First among Private Iraqi Universities