Water exhibits an anomalous expansion property. Unlike most substances which become denser as they cool (contracting), water’s density increases as it cools from boiling point down to 4°C. However, when cooled further from 4°C down to 0°C, it expands and its density decreases. At 0°C, when it freezes into ice, its density drops significantly. Therefore, the density of water is maximum at 4°C.Water has maximum density at 4°C. This anomalous expansion is crucial for aquatic life in cold climates, as ice floats and water at 4°C remains at the bottom of lakes, preventing them from freezing solid.The density of pure water at standard atmospheric pressure is approximately 999.97 kg/m³ at 0°C, 1000 kg/m³ at 4°C, and decreases gradually as temperature increases beyond 4°C. Ice (solid water) has a density of about 917 kg/m³.