Icon holding tanks are thermoformed of high impact ABS plastic. All seams are solvent welded and have a 1-1/4 in. mounting flange around the perimeter for easy installation. The HT706ED Holding Tank from Icon features a center end drain and a 15 Gal. holding capacity. The dimensions of this tank are 46.5 in. x 16.5 in. x 8 in. Comes with 3 in. spigot fittings and four level sensors installed on the tank.