Dewatering is a process of removal of water from a foundation pit when it is situated below the ground water table or when it is surrounded by a cofferdam. The purpose of dewatering is to keep the excavation dry so that concreting can be done. Dewatering is temporary if it is done at the time of construction. It is followed by restoration to its original water table after the structure has been be completed. Permanent dewatering is required for removing subsurface gravitational water throughout the life of the structure. It may be necessary to keep the water away from the structure to check the dampness or other ill effects.
