Department of
Environmental Quality

Thousands of homes in Idaho are heated with heating oil stored in underground tanks on the owner’s property and thousands more have old heating oil tanks that are no longer used buried on the property.  Many of these unused tanks still contain heating oil.  While heating oil tanks are not federally regulated under UST regulations, a leaking tank can harm the environment and may be subject to state cleanup requirements.

It takes about 30 years before corrosion will make an underground heating oil tank prone to leaking; however, the life of an individual tank can vary widely depending on the properties of the surrounding soil. A leaking underground heating oil tank can contaminate the environment and cause problems for the landowner.  Even tiny amounts of heating oil left in a seemingly empty tank can leak.  Potential problems caused by a leaking tank can include:

• Liability. The property owner can be held liable for damage caused by contamination from the tank.
• Soil Contamination. Leaks can contaminate soil on the site and neighboring property.
• Water Contamination. Leaks can contaminate ground water and possibly the residents’ well water.
• Cave-Ins. Cave-ins can happen when tanks deteriorate from corrosion and the tank walls collapse.

In addition, more and more lending institutions and buyers require closure of unused heating oil tanks before they will finalize a residential sale.  Even if you don’t intend to sell the property, you may want to consider closing the tank for your own protection. 

If your heating oil tank is still in use, watch for signs that it may be leaking, such as your furnace using more fuel than usual (consider other possible reasons as well, such as unusual weather or furnace malfunction.)  You may also wish to actively check for leaks. 

For more information on closing a residential heating oil tanks and checking for leaks, see Real Estate Professionals and Underground Storage Tanks or contact your local DEQ Regional Office.