Water is a key factor influencing the concrete durability including corrosion of reinforcement. In order to study the water content in concrete the electrical resistivity, due to its sensibility to water, is considered to be one of the most efficient non-destructive solutions. This paper describes a novel method of resistivity measurement developed in laboratory using four-probe array. This technique allows the study of the water content in function of depth in concrete structures. Impacts of reinforcement steels and cover depth on measurement are also studied by measurement over the rebar. Results show that the presence of reinforcement modifies significantly concrete resistivity. This technique also shows the interest of measurement to evaluate the water content gradient in concrete.