Over _______________ USTs in the U.S., regulated by the EPA, contain petroleum or hazardous wastes.

• A. One thousand
• B. One million
• C. One hundred thousand
• D. Ten thousand

Answer: (B)

Underground storage tanks regulated by the EPA are numerous because they are used across many sectors to store fuels and other hazardous liquids. The figure over one million reflects the broad reach of these tanks—from gas stations to large industrial facilities and heating oil systems in homes and businesses—across the entire country. This scale makes sense when you think about how many sites rely on buried tanks for everyday operations. The large number underscores why EPA rules focus on preventing leaks and detecting releases to protect soil and groundwater. The other, smaller numbers don’t capture the nationwide footprint of regulated USTs, so one million is the best fit.