Whether your foundation rests on land with a high ground water table or the area has been inundated with rain or melting snow, whether the water comes in at the bottom of the wall where it meets the floor or through cracks in the floor itself, exterior drain tile is your first line of defense against ground water seepage and a wet basement.
Most homes built during the early 1980s and after have exterior drain tile, or more accurately, drain "piping", installed around the footing of the foundation walls. Drain tile collects and channels water to a centralized area (an interior sump pit or exterior well point) so that it can be discharged by a pump and directed away from the foundation before it can migrate under the foundation and into the basement. Over time, settlement, roots, silt, etc. can clog or even damage the tile and the resulting build-up of water under and/or around the foundation can eventually force its way in. Repairing exterior drain tile requires excavating a trench along the foundation wall, down to its footing. Occasional inspection of the interior perimeter of your basement floor to look for damp spots, staining or other signs of water intrusion is prudent.
Interior drain tile can also be installed when necessary. Approximately 12" of the concrete floor, where it meets the wall, is removed and the ground below is dug out to expose the footing. Drain tile is then placed in between two layers of gravel and tied into a sump pit or gravity fed discharge system. The concrete is then replaced. This is an extremely effective repair but usually made only when installing exterior tile is problematic. Because this type of tile allows water into the interior of the structure, serious consideration must be given to flooring choices and other finishes due to the presence of ground water and its vapor which will be transmitted through the floor.