DC-900500-1.2, Duracast 500 Gallon Plastic Water Tank | 900500 These rotationally molded plastic tanks are perfect for storing large quantities of water. Durable and safe, you can use these tanks to collect and store rainwater or to hold a large supply of potable water. People commonly store water for later use for spare drinking water, irrigating crops, domestic purposes or emergency situations. These tanks are manufactured with FDA-approved polyethylene resin so they will not contaminate the water. The UV stabilizers compounded into the resin to reduce sun damage. To keep your water fresh and slow the growth of waterborne algae outdoors, store water in black or green tanks. Use the gallon calibrations molded into these tanks to keep track of content levels, and determine when tanks need to be refilled. This is a 1.2 specific gravity tank.