The main source of degradation of underground or partially underground places is water originating from infiltratrion, from the water table or from normal moisture present in the earth on which foundations are laid. In addition to the high level of damp which makes places inhabitable, the salts dissolved in water cause plaster to become loose. In the most serious cases, in the presence of the water table, the water tends to reach the same level inside the building as the external level through fissures and empty capillaries.