It is estimated that 90% of all homes having cinder block basement walls will leak in the first 25 years of their life and one home in 300 have problems related to natural ground water tables. Homes having basements are generally constructed on concrete footings upon which concrete or block basement walls are constructed. This involves digging a large hole in the ground in which the basement of the house to be built. In the bottom of the hole, trenches are dug into which concrete is poured for the footings. The basement wall is then constructed on these footings. Basement walls are generally constructed of concrete block or cinder block. However, basement walls of poured concrete, brick or other materials are sometimes used. Depending upon the local building codes, the builder may be required to parge the exterior face of the wall. Parging usually consists of applying a Portland cement-sand mixture to the outside surface of the basement wall. Application of additional materials such as asphalt coatings covered with polyethylene sheeting, over the parging, generally completes the waterproofing process. .

Typically, flooding occurs as a result of surface water infiltration in the following manner:  The rainfall collects (ponds) on the ground surface adjacent to the home. Water, by taking the path of least resistance, flows into the loose backfill adjacent to the basement walls
If the undisturbed soils surrounding the house are relatively impermeable and a properly functioning under drain system is not present, this water will collect in the backfill soil. Water pressure then builds up against the exterior of the basement walls. The condition of the exterior waterproofing now becomes critical. If it is in good condition, the water may build up sufficient pressure to crack the basement walls and allow the water in. If the exterior basement waterproofing has deteriorated at any point, the water will enter there. In either case, the water will be making a continuous effort to relieve the pressure it has built up on the outside of the basement walls by leaking into the basement. Since block walls are hollow, a defect on the exterior surface of the wall may result in the lower courses of block becoming filled with water. If the interior side of the block is sound, this condition may go unnoticed for a considerable period of time until the interior surface begins to leak.