A clogged footing drain will not collect any more water. So the water puddles up into the backfill and starts pushing against your home. The weight of the water creates pressure which pushes against your foundation – this is also called hydrostatic pressure.
The hydrostatic pressure pushes the water into the porous concrete and through cracks in the block or mortar. Over time the hydrostatic pressure, soil settlement and seasonal changes can result in basement wall cracks or cracks in the poured concrete.