Analysis of water table records from wells or boreholes often reveals the presence of tidal fluctuations. Amplitudes of ‘well tides’ can attain several centimeters when the well or borehole is open to a confined aquifer. The phenomenon reflects extension and compression cycles of the aquifer rock, i.e. volume strain tides of a water saturated formation. Besides tidal fluctuations, barometric pressure changes and pure loading effects may be observed in well level records. If the forcing functions are known, these signals can be used to constrain petrohydraulic aquifer parameters of the connected formations. Linear poroelasticity is the commonly used rheology to describe the underlying physical process; or elastic deformation of fluid filled fractures in case of low permeable rock with a few fractures that are open to the well.