The expansion of water when it is cooled from 4°C to 0°C,is known as anomalous expansion of water. On cooling water, the density of water first increases up to 4°C and then decreases when it is cooled below 4°C to 0°C and thus volume increases resulting in expansion of water.The density of water is maximum at 4°C which is equal to 1g/cm³(or 1000kg/m³) and the volume of water is thus minimum at 4°C equal to 1cm³.