What happens to the volume of water as it is cooled from 3 degrees Celsius to 1 degree Celsius?

Water is most dense at 4 degrees C, after which the molecules will begin to arrange themselves in the open hexagonal structure. This will result in an increase in volume. Also, because the density is decreasing, using the formula for density: D = m/V Solving for V: V = m/D Because the mass remains constant, and the denominator, density, is decreasing, the volume will be larger.