Abstract—Deformation regimes of water-saturated reservoirs under dynamic impact are studied using groundwater-level monitoring by precision measurements. As a quasi-stationary factor responsible for background poroelastic groundwater-level fluctuations in the reservoir–well system, the Earth’s tides are considered. Hydrogeological responses to the passage of seismic waves from remote earthquakes and mass blasts produced during iron ore mining are used for estimating relative deformation of water-saturated reservoirs. The study objects are located both outside the zone of active manmade impact on geological environment (in the territory of Geophysical observatory “Mikhnevo” of the Institute of Geosphere Dynamics of the Russian Academy of Sciences) and in the technogenically disturbed conditions—in the industrial region near Gubkin, Belgorod region. Integrated processing of seismic, barometric, and hydrogeological data synchronously recorded by the instrumental-measuring systems installed in the observation wells and at the near-head sites is aimed at revealing common regularities in the responses of water-saturated reservoirs to a dynamic impact. The comparative analysis of the amplitudes of groundwater level fluctuations and pressure variations in the reservoir–well system is carried out with the allowance for ground motion velocities and reduced distances from the remote earthquakes and mass explosions. The response of water-saturated porous- and fractured-porous type reservoirs is different. Alongside with the coseismic hydrogeological effects, the analysis revealed a postseismic groundwater-level rise and increase in pressure indicating a local change in the poroperm properties of a water-saturated reservoir. The maximum values of seismic-wave ground velocities and pressure in the reservoir–well system at which deformation regimes change from a poroelastic to quasi reversible response are established.