Due to military operations in Ukraine, there is an increasing need to utilize structures such as reinforced concrete tanks for storing drinking water. The researched facility was built in the 1970s and is currently not operational; it is classified as unfinished construction. Visual inspection revealed a significant violation of its tightness. Before the full-scale test, a visual and technical inspection was conducted on the water storage tank. This inspection aimed to assess its technical condition, measure its geometric dimensions, identify the materials used in the supporting structures, and evaluate the type of structural scheme employed. A full-scale (control) test was conducted by gradually filling the storage tank with water. According to the research results, the possible appearance of new cracks and the width of their opening were recorded, measurements of probable structure settlement were made (levelling was carried out), and the bending (deformation) of the open end walls was measured. The tank’s filling process was closely monitored, and water consumption was recorded to identify any leaks during the holding period. Based on the research and full-scale tests carried out, conclusions were made regarding the possibility of reconstructing the reinforced concrete tank, along with recommendations for its continued safe operation.