What do underground storage tanks (USTs) primarily store?

Underground storage tanks (USTs) are primarily designed to store substances such as petroleum products, chemicals, and other potentially harmful materials. These tanks are commonly used for the storage of fuel, including gasoline and diesel, as well as hazardous materials that need to be kept out of sight for environmental and safety reasons. Because these substances can pose significant risks to human health and the environment, the regulation and proper management of USTs are critical.

The other options do not accurately reflect the primary purpose of USTs. While food and beverage products, residential waste, and air and water may be stored in various containment systems, they are not typically stored in USTs, which are specifically engineered for hazardous or potentially harmful substances.