Why basement leaks?

Ground water builds up around your foundation causing hydrostatic pressure. This pressure causes it to force through the joint between your basement wall and footer. This pressure will cause penetration in floor cracks, wall cracks, and pipe penetrations. Etc.

Basement Water Sources

Wet basements are found throughout the country from new construction to old homes. The areas adjacent to the foundation are the most critical in diverting water or actually causing the problem. The grade or dirt level should always be pitched away from the house and the downspouts should be run a minimum of 8 feet or as far as necessary to ensure water runs away. 
As the water saturates the ground it causes hydrostatic pressure. This pressure is what causes water to force its way into the basement through the wall/floor joint, cracked floors, wall cracks and pipe penetrations. An older houses floor drain is yet another entry point. 
Having an interior water management system including french drains, wall drains and sump pumps is the choice of basement waterproofing professionals everywhere.

Hydrostatic Pressure is a term used in waterproofing that explains the process in which ground water becomes more pressurized with depth; this process is what causes ground water to force its way into your crawlspace or basement.

To relieve hydrostatic pressure, you will need to tap into the source of the water, which is done by drilling weep holes into the bottom row of blocks, allowing the water to drain. Once the water has drained you can install a proper french drain to collect the water and carry it to a sump pump to be ejected from the basement.