The two common fuels stored in residential USTs are propane and fuel oil. Propane vaporizes quickly and does not pose a groundwater contamination threat. This is why testing of underground propane tanks is not necessary in most cases. But fuel oil can potentially contaminate ground water sources--the source of potable water for approximately half the American population.
Fuel oil storage tanks have been used for many years. Prior to the mid 1980’s, bare steel was used to make underground storage tanks (USTs). Bare steel in a moist, underground environment will eventually rust and/or corrode. Many tanks were also improperly installed by untrained persons or simply not meant for underground use. As a result, these original fuel oil USTs are very likely to leak at some point, if they are not leaking already. The average life of a UST is considered to be between 12-20 years. Most of the old bare-steel USTs are well beyond that age.
Congress passed legislation banning the installation of “unprotected steel tanks and piping” in 1985. The exterior and components of USTs installed after 1985 must be corrosion-resistant and resist the effects of pressure, vibration, and movement. The EPA also instituted regulations that placed the responsibility of storage tank leaks on the tank owner or operator. Not all USTs must meet federal EPA regulations, including most residential USTs, but some state and/or local authorities have separate requirements, so it is best to check with them first. Some states even require the homeowner to have the tank tested on a regular basis.
For more information about USTs, click here.