A.Don Marsh responds: There’s no question the holes must face down (oriented approximately at 4 o’clock and 8 o’clock) to drain off any water rising from below. Keep in mind that if the drain is embedded in stone, as it should be, water will run through the stone as well as through the drain. In other words, the stone and pipe work together to drain the water away. You aren’t limited to just the narrow trough of water between the holes in the pipe.
The drain should be placed at least 6 inches below the interior slab. If the holes were facing up, you might be able to carry off more water through the pipe itself, but in order to get into the pipe, the water level would rise dangerously close to the slab.
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