During my home inspections I sometimes find indications of a past used oil tank. Old oil tank fuel lines in the basement are a tell tale sign that an oil tank has been on the property at one time. The questions that remain to be answered are if the tank is still there, if the tank has been removed and is no longer there; and if and when the oil tank was removed or is still in place, was it properly decommissioned?
If there are questions that remain as to if and when there were or still is an oil tank on the property that you would like to buy, the best thing you can do for yourself is to have the property scanned for underground metal tanks. The are speciality companies that will come out and do this for a modest service charge. The service person walks the grounds near the house and looks for any indications of a large metal mass. If found, the next step is to probe and actually find the tank using a large metal probing bar. Then finally to outline the perimeter of the hidden tank.