The intended performance of hydraulic structures such as dams built on soluble rock or soil foundations may depend upon rates of dissolution caused by water seeping through joints, fissures or granular zones. Previous papers by one author and collaborators have defined the rates of dissolution for soluble rocks by means of a simple equation: dM/dt = K A (Cs—C)θ. This relationship may be used as an aid to prediction of enlargement of joints and fissures in rocks, settlements of granular foundation strata, the deterioration of filters, risks to shallow but intensely loaded foundations, and durability of underground storage caverns in soluble rocks. The relationship requires a knowledge of the solution potentials of groundwater associated with these features of engineering structures. They in turn require an understanding of the relevant hydrochemistry and hydrology which is discussed in this paper.