Whether you have an underground or an above-ground tank, even if it's in your basement. Old tanks can quickly become a hazard if not maintained and checked regularly.
If you don't use your tank anymore, consider removing it. When removing an old tank NFPA recommends the tank and any related piping to be disconnected, emptied of contents, cleaned, and then removed from the premises and disposed of following local regulations. This includes the removal of the outside fill and vent lines.
