In light of the ongoing depletion of sand and freshwater resources, the utilization of seawater and sea sand in concrete applications has been greatly paid attention. However, the susceptibility of reinforced steel to corrosion poses a critical challenge in the context of reinforced concrete structures incorporating these materials. It is reported that elevated water salinity, exceeding 3.5% in typical seawater, can lead to a reduction in the corrosion rate of steel. This study focuses on investigating the steel corrosion in mortar containing water with salinity exceeding 10% using NaCl salt, with the overarching goal of mitigating steel corrosion in reinforced concrete with seawater, sea sand and additional salt. Initially, the corrosion of deformed rebars immersed in water with NaCl salinity levels of 0, 3, 10 and 20%, were studied, considering two pH conditions. Notably, irrespective of pH conditions, the corrosion mass loss rate was minimized at a NaCl salinity level of 20%. Subsequently, the corrosion in mortar using mixing water with NaCl salinity levels of 0, 3, 10 and 20% was examined. The accelerated electrolytic corrosion test revealed that the corrosion of steel within the mortar was most effectively suppressed when the NaCl salinity of the mixing water was 20%.