There are several geotechnical and geoenvironmental problems involve water FLOW through soils. The coefficient of permeability is the most important parameter that dominates the water FLOW pattern through soils, both in transient and steady state conditions. In the current paper the STRESS dependency of permeability and its effect on the ground water FLOW is evaluated. The results of a field instrumentation program to establish pore water pressure profile is presented and the dominant effect of STRESS dependent permeability characteristics of soil over ground water pressure and FLOW is demonstrated and compared with an analytical solution. Also, the procedure and results of a laboratory experimental work to evaluate STRESS dependency of permeability is elaborated. Finally, referring to the site and laboratory investigations the nature of STRESS dependent permeability of soil and the validity of the related equation are assessed.