Home fuel oil storage tanks are generally classified as aboveground or underground. Underground tanks or USTs, are buried in the yard. Aboveground tanks, ASTs, are typically located outside the house, in a crawlspace or in the basement.
Tank sizes range from 275 to 1,000 gallons with 275 gallons as the most common. Fuel Oil No. 2 is the most common type of oil used to heat homes in the United States and is basically diesel fuel with dye.
When fuel oil is properly stored and used, it is safe. Even though the oil has low toxicity to humans, its fumes can be harmful. A tank should be inspected regularly for leaks.