The work studies not salted Sarmatian clays from the Central Moldova. Laboratory modeling of a long-time influence the water has on clays is executed. Changes of structure and properties of Sarmatian clays owing to diffusive leaching for 3 months are analyzed. Typification of a clays according to their resistance to flood is developed and the technique of the forecast of durability indicators of the clays which are exposed to flood in foundations of buildings and constructions is offered.