Given that the basement is below ground, it stands a higher chance of water leakage than other parts of the home, save for perhaps the kitchen or bathroom. It’s important to keep this area from getting standing water though, as to prevent mold and mildew from forming on the structural formations that hold the home up.
The best solution is to prevent water from getting under the house in the first place. That's because moisture causes problems with wood, and water may excessively soften the ground around the foundation. To keep water out, dig ditches around the high sides of the house down to the footings. Install gravel and drain lines. Slope the lines about two inches per 10 feet to carry water away from the house. Direct the water to a natural drainage, to the street, or to a French drain in the yard. Before you backfill, you should be sure to place waterproof membranes against the foundation wall. Of course, make sure that water from downspouts is directed well away from the house at all times.
If condensation or small puddles build up after rain or snow storms, it’s best to handle standing water like these with cloths and fans. In extreme situations, you’ll need to find the source of the leaks and seal them with spackling or other foundation cement to keep further leaking from occurring in the future.
A sump pump is another answer. The best choice is a completely submersible pump with a float arm that activates the pump as water rises to a certain height in the sump. But buy the sump pump first, available at home supply centers. The size of the sump, which is the hole that collects the water, will be determined by the size and type of sump pump you have.
Dig the sump at the low end of the crawl space (or basement), where most of the water collects. One easy way to do this is to buy a plastic bucket large enough to readily hold the pump and not block the arm movement, which must float free. Drill holes all around the bucket's sides and bottom, and set it on some pea gravel in an appropriately sized hole. Backfill around the bucket with pea gravel also. If necessary, do some ditching in the crawl space to direct water to the sump.
Since the pump needs electrical power, an outlet protected by a ground-fault circuit interrupter is needed nearby. Finally, attach PVC piping to the pump to carry the water out of the crawl space to the storm drains, a natural drainage away from the house, or a French drain in the yard.