How to best fix your rainwater drainage? In the high desert climate of Santa Fe, and much of the arid West, utilizing rainfall through a catchment system has long been an essential part of conserving our natural resources. Drainage products manage rainwater by collecting the water and moving it to areas where it can soak into the ground. Collection is done using square/round grates or longer narrow grates called channel drains. Gravity flow moves the water through PVC or flexible corrugated plastic pipe to spots where it either discharges onto the ground & soaks in, or empties into an underground French drain.