Waterproofing concrete is used for buried parts of the structures, especially in buildings. This type of concrete is permanently in direct contact with the underground water. The concrete water sealant capability depends on many factors, but mainly on the porosity of the cementitious material. The soil granulometry and the load bearing capacity were tested before the placing of a water proofing concrete basement. A water sealant compressive strength class concrete C 30/37, with a maximum aggregate size of 32 mm was targeted. After 18 months of service life, the basement and the vertical walls of the buried parts of a building complex exhibited a relevant visible crack pattern, with the presence of widespread cracks across the entire basement thickness of 30 cm. The concrete water sealant requirements force the achievement of a high early strength with a relatively medium-high stiffness on a short-term, a high cement dosage and high quality rigid siliceous-calcareous aggregates. The waterproofing concrete shrinkage was doubled as compared to a similar strength class concrete C 30 /37. The dense matrix, the high early strength and medium-high stiffness, the lack of a sufficient sealant joints frequency, the relative high water pressure from the underground water and the occasional, but intense water underground run offs, caused the premature cracking failure for most of the basement and the elevation walls, with a relevant water infiltration from the zones in contact with the ground. Injections partially solved the water infiltration, that needs to be periodically monitored.