Icon holding tanks are thermoformed of high impact ABS plastic. All seams are solvent welded and have a 1-1/4" mounting flange around the perimeter for easy installation. The HT700SD Holding Tank from Icon features a center side drain and a 31 gallon holding capacity. The dimensions of this tank are 54.5" x 26.5" x 9". Comes with 3" spigot fittings and four level sensors installed on the tank.