A French Drain is a hidden piping and drainage system which can trap
water before it enters your house or other areas around your home or business.
Negative slope causes a majority of basement or crawl space drainage
problems. It can also cause problems for houses built on slabs. Houses built on hillsides often are victims of negative slopes
as the ground uphill from the house directs surface and ground water directly at the structure.
This French Drain, in the images directly below, was installed to collect sub-surface
water around the pool area.