A large (usually metallic) vessel for holding gases or liquids(noun)
WordNet. Princeton University. 2010.
Use "storage tank" in a sentence
"As Tom looked about, trying to spot Eskot, he saw the saboteur run from the side door of a tool shed toward the ladder of the storage tank which contained fuming nitric acid."
"To fill the still again, we wrestled more of the heavy 3-inch red food-grade hoses around the room and ran a line between a tanker-truck—sized dairy storage tank full of Oskar Blues wash and the empty still."