A comparison study between the treated produced water and fresh water was performed to test their effect on soil physical and chemical properties. Large quantities of water are produced during oil extraction in Oman. This water is utilized for reservoir pressure maintenance by injection into shallow and deep sub-surface formations at oil fields. Because of the salinity in water, treated water was found to have significant effect on the electrical conductivity of the soil saturation paste extract with no significant effect on the pH of the soil. It has been found from the study that the use of treated water caused sodicity problem, which had adverse effects on the physical properties of the soil such as pore size distribution, infiltration rate and saturated hydraulic conductivity. No significant difference was observed in heavy metals accumulation when fresh and treated water were used.