In arid and semi-arid regions, wastewater treatment and reuse have become an important element in water resources planning. Some researchers believe that the use of treated wastewater for agriculture is an appropriate method because plant nutrients will be returned back to the soil and the environmental pollution and pollution to the water resources will be reduced. The use of treated wastewater for irrigation requires that factors such as salinity to be considered. The soil salinity is an important factor which reduces crop production and also decreases the area under cultivations. One of the problems of irrigation in arid and semi-arid regions is the accumulation of salt in soil profile. Due to limitation of available water for agriculture, the use of low quality water for irrigation is increasing. One of the effective methods to reduce soil salinity is leaching and leaching management. Few studies are available about the leaching of soils irrigated with wastewater. Therefore, it is necessary to study the leaching requirements of these conditions. In this study the effect of two irrigation water treatments of well water and wastewater, with three salinity levels of 1, 3.5 and 6 dS/m and three leaching levels of 10, 20 and 30%, on chemical characteristics of soil and drain water were studied for a sandy loam soil using experimental soil columns. The experiments were conducted at the greenhouse of College of Agriculture, Isfahan University of Technology using factorial design with three replications. The electrical conductivity and cations (Na + , Ca 2+ , and Mg 2+ ) of drain water and soil were analyzed for both irrigation water treatments at the beginning, middle and end of the experiments. At salinity levels of 1 and 3.5 dS/m, there were no significant differences of electrical conductivity of drain water between two irrigation water treatments for the beginning, middle and end of the experiments. At salinity level of 6 dS/m, and leaching levels of 10, 20 and 30%, toward the end of experiment; the difference between electrical conductivity of drain water of two irrigation water treatments became significant. At the end of the experiment, soil samples were taken from soil depths of 0-15, 15-30 and 30-45 cm and their chemical characteristics were determined. At salinity levels of 1 and 3.5 dS/m, and for all leaching levels, there were no significant differences between electrical conductivity of soil of two irrigation water treatments. At salinity level of 6 dS/m, at the leaching levels of 10 and 20%, the differences between electrical conductivity of soils of two irrigation water treatments were significant, but at the leaching levels of 30%, the difference was not significant. The use of wastewater for irrigation requires proper management in order to prevent soil salt accumulation. Keywords: Wastewater, Saline water, Leaching, Salt balance, Electrical conductivity