DC-910500-1.2, Duracast 500 Gallon Plastic Water Tank | 910500 Water storage is safe and convenient with Duracast’s 500 gallon plastic tanks. These vertical tanks are made of FDA-approved polyethylene resin so that you can store potable water safely. To slow the growth of waterborne algae, use black and green colored tanks outdoors. These tanks are low-maintenance, easy to clean and lightweight. Access the 16-inch vented lid to fill and clean tanks. To measure contents quickly and easily, these tanks feature gallon calibrations molded into the plastic. People can use these tanks for irrigation purposes, emergency water supply, well storage and to collect rainwater. This is a 1.2 specific gravity tank.