Dynamics of water in Prussian Blue Analogue Cu_0.75Mn_0.75[Fe(CN)₆].7H₂O molecular magnet is studied using quasielastic neutron scattering technique. Significant quasielastic broadening corresponding to the dynamics of water molecules existing in the cavities created by the absence of Fe(CN)₆ units is observed in the temperature range 260-360 K. While all the non-coordinated water molecules at 32f site are found to be dynamic over the entire range of temperatures, the coordinated ones become progressively dynamic as the temperature increases. Localized translational diffusion model is found to describe the dynamics of the water molecules. A consistent picture of dynamics of the crystal water in this molecular magnet system is given for the first time.