Water mobility through porous rock has a role to play in many systems, such as contaminant remediation, CO2 storage, and oil recovery. We used inelastic and quasielastic neutron scattering to describe water dynamics in two different chalk samples that have similar pore volume (ranging from tens of micrometers to a few nanometers) but different water uptake properties. We observed distinct water populations, where the analysis of the quasielastic data shows that after the hydration process most of the water behaves as bulk water. However, the lack of quasielastic signal, together with the observation of a translational mode at 10 meV, imply that in chalk samples that take up less water confinement occurs mostly in the pore volume that is accessible with nitrogen adsorption measurements.