DC-905000-1.2, Duracast 5000 Gallon Plastic Water Tank | 905000 When storing water, use Duracast’s plastic tanks to keep water clean and safe. Duracast tanks are made of FDA approved polyethylene resin, which means you can use these tanks to store potable water. Black and green tanks block out the green spectrum of light and slow the growth of waterborne algae. These tanks are rotationally molded to be a one-piece container and do not have any seams, joints or welds that typically cause leaks. Because these tanks are made of UV -tabilized resin and have outstanding low temperature impact strength, you can keep them outdoors. A 16-inch vented lid provides access for cleaning and filling tanks. This is a 1.2 specific gravity tank.