Pool Drain Pipe made by Overflo 3001 Installation Instructions: Cut an area across Bondbeam, 5 inches wide and 1 inch deep at inside of swimming pool. Extending to 3 inches in diameter at outside of swimming pool. Place the rectangular opening 1/2 inch beyond Bondbeam inside of swimming pool (for tile allowance). Position rear 3 inch diameter opening slightly downward for gravity flow. Use waterproof mastic or grout to secure Overflo, keeping rectangular opening just under the bottom of the coping, other capping or cantilever deck. Attach 3 or 4 inch drain line to Overflo for dispersal to drainage area.