Usually, the pores and fractures are connected so that the water in the rock can move in response to pressure changes.
Fractures have high permeability and allow water to move quickly from place to place.
This distinction has no scientific foundation it is based solely on the concept that water above this arbitrary temperature is an energy resource it is not possible to clearly separate geothermal water from cold groundwater on the basis of temperature alone. These waters form convective, hydrological systems within the upper part of the crust which are driven by the heat sources. In both cases, in their natural state, these are dynamic systems the hot water is continually being lost at the surface to rivers and being replaced from deeper in the earth. The chemical composition of low-temperature tectonic geothermal waters is influenced mainly by the chemistry of the rocks the water has come into contact with, and the temperatures to which the water has been raised. The fluids within rocks with which the water interacts will also influence the chemistry.