storage tank

A storage tank is a construction or a container, usually for holding liquids, sometimes for gases. The term can be used for both reservoirs (artificial lakes and ponds), and for manufactured containers. The usage of the word tank for reservoirs is common or universal in Indian English, and moderately common in British English. In other countries, the term tends to refer only to artificial containers.
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Noun
1. a large (usually metallic) vessel for holding gases or liquids
(synonym) tank
(hypernym) vessel
(hyponym) aquarium, fish tank, marine museum

A container for storing a hazardous fluid, including an underground cavern. (49CFR193)