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Please note: This summary is provided to help you understand the regulations. Consult the references provided for links to the full text of the regulations.

USTsUnderground Storage Tanks (USTs)

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This section covers regulations for underground storage tanks used for petroleum fuel storage.


iconA tank does not have to be completely buried to be an "underground tank". According to the rules, if a tank, and any underground piping connected to the tank, has as little as 10 percent of its combined volume underground, it is considered an "underground storage tank system" and is covered by UST regulations.

Who is covered by the regulations?

Federal UST regulations apply to underground tanks storing more than 110 gallons of either petroleum or certain hazardous substances.

State UST regulations also exist, most of which are similar to the federal rules. However, some tanks that are excluded under federal rules may be covered by some state rules, and some state rules may be more stringent than federal rules.

What is the purpose of the regulations?

There are approximately 600,000 active underground storage tanks (USTs) nationwide that store petroleum or hazardous substances and there have been nearly one-half million confirmed releases from USTs. Leaking underground storage tank systems pose a significant threat to groundwater quality in the United States, which supplies drinking water to approximately 50 percent of the nation's overall population and 99 percent of the population in rural areas.

Any tank can leak, and underground tanks present particular challenges because leaks can go unnoticed. Small leak rates can become major releases over time. Both at federal and state levels, UST regulations are intended to address leaks preemptively, by requiring facility operators to act before leaks occur. The rules require facility operators to develop plans that generally include effective monitoring of petroleum and chemical storage systems. In addition, the rules impose deadlines for removal of older USTs, so they can be replaced, before they fail, by systems built to present standards.


The federal regulations for underground storage tanks can be found at 40 CFR 280. Below is a

iconPlease note: EPA may strengthen the federal UST regulations by increasing emphasis on properly operating and maintaining UST equipment. More information.

brief summary of the requirements with links to specific sections of the regulations.

If your facility has a regulated underground storage tank, you must take these steps:

  • Register UST systems that store more than 110 gallons of gasoline, diesel fuel, motor oil, used oil, or other regulated substances.

  • Any UST installed after December 22, 1988, must meet the requirements for new USTs concerning correct installation, leak detection, and spill, overfill, and corrosion protection.

  • Any UST installed before December 22, 1988, must meet two major requirements:

    • By December 1993, the UST must have leak detection.

    • By December 1998, the UST must have spill, overfill, and corrosion protection.

  • You must take corrective action in response to leaks.

  • You must follow closure requirements for tanks you temporarily or permanently close.

  • You must demonstrate your financial responsibility for the cost of cleaning up a leak and compensating other people for bodily injury and property damage. You need either $500,000 or $1 million in "per occurrence" coverage and either $1 million or $2 million in "aggregate" coverage, depending on your ownership category. These requirements are briefly summarized in an EPA booklet, Dollars And Sense.

In June 2015, EPA issued the 2015 underground storage tank regulation and the 2015 state program approval regulation. The revisions strengthen the 1988 federal underground storage tank (UST) regulations by increasing emphasis on properly operating and maintaining UST equipment.

The 2015 regulation changes certain portions of the 1988 underground storage tank technical regulation in 40 CFR 280. The changes establish federal requirements that are similar to key portions of the Energy Policy Act of 2005. In addition, EPA added new operation and maintenance requirements and addressed UST systems deferred in the 1988 UST regulation. The changes include:

  • Adding secondary containment requirements for new and replaced tanks and piping
  • Adding operator training requirements
  • Adding periodic operation and maintenance requirements for UST systems
  • Adding requirements to ensure UST system compatibility before storing certain biofuel blends
  • Removing past deferrals for emergency generator tanks, airport hydrant systems, and field-constructed tanks
  • Updating codes of practice
  • Making editorial and technical corrections
  • The 2015 state program approval (SPA) regulation also updates SPA requirements in 40 CFR part 281 and incorporates the changes to the UST technical regulation listed above.

EPA recognized that, because of the size and diversity of the regulated community, state and local governments are in the best position to oversee underground storage tanks. Therefore, most states have assumed responsibility for USTs (for more information, see state program approval process). State programs must be at least as stringent as the EPA UST regulations.

All 50 states and the District of Columbia have approved "state" programs. EPA provides separate web pages listing the status of each state, together with statistics and contact information.

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Compliance Options

One way to avoid the expense of compliance with UST rules is to consider closing your USTs all together.

If you could be sure you would have access to fuel 24-hours a day at a conveniently located station, would you still need your USTs? Such an arrangement would transfer the responsibility of complying with UST rules to the operator of a dedicated facility who has presumably built compliance into the operation from the beginning. In addition, the billing systems now used by many motor fuel suppliers may enable you to track fuel usage more closely than you do at your on-site facility.

Another option is to consolidate your own and other companies' refueling facilities at a single site convenient for all your vehicles. This site could have unattended fuel pumps activated by key cards, so that you would receive detailed records of refueling by your employees.

These options can reduce or eliminate your responsibility for petroleum releases, costly cleanups, and liability insurance. In addition, if you remove all your USTs in favor of off-site refueling, you will also avoid some of the environmental concerns that sometimes block property transfers or make bankers reluctant to lend money.

You can close your UST temporarily or permanently. In either case, tanks must be closed properly. EPA provides a web page with additional information on tank closure.

Best Practices

The following are prevention measures to prevent and detect UST releases. Please note that some of these measures are required by federal and state regulations:

  • Stop using and close (e.g., remove or fill in place) all single-walled steel USTs lacking cathodic protection that are over 25 years old.

  • Properly install USTs according to industry standards with great care to maintain the integrity and the corrosion protection of the tank. Tanks must also be properly sited away from wells, reservoirs, and floodplains.

  • Do not install, close, or upgrade a UST system without first obtaining federal or state approval.

  • Equip all UST systems with spill containment devices. USTs must have catchment basins that can catch spills that may occur when the delivery hose is disconnected from the fill pipe. A catchment basin is basically a bucket sealed around the fill pipe.

  • Equip all UST systems with overfill protection devices. When a UST is overfilled, large volumes can be released at the fill pipe and through loose fittings on the top of the tank or a loose vent pipe. USTs must have overfill protection devices, such as automatic shutoff devices, overfill alarms, and ball float valves. In addition, proper filling procedures during fuel delivery must be followed to reduce the chance of spills or overfills.

  • Implement leak detection procedures. Detection methods include monthly inventory reconciliation, statistical inventory reconciliation, tank tightness testing, manual tank gauging, automatic tank gauging, interstitial monitoring, vapor monitoring, and ground water monitoring. All leaks must be detected in a timely manner, before they become big cleanup and liability problems. Upon discovery of a release, the owner or operator must report it.

  • Make sure UST systems are made of non-corrodible material, such as fiberglass, or have corrosion protection provided in other ways, such as being made of externally coated and cathodically protected metal, having double walls, metal having a thick corrosion resistant cladding or jacket, or having an internal tank lining.

  • Label the fill pipe with the name of the regulated substance contained in the tank.

  • Do not mix different types of substances in the same tank.

  • Protect UST fill and vent pipes from being hit by vehicles and other equipment, including snow plows, fork lifts, tow trucks, flat beds, customer vehicles, and the like.

  • Keep tank fill pipes closed, except when adding or removing product.

  • Keep spill control equipment nearby. Immediately contain and clean up spills and leaks.

  • Immediately report large or uncontrolled spills.

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More Resources

EPA Office of Underground Storage Tanks (OUST). Management of underground storage tanks (USTs) for petroleum and other products, response to tank leaks, and reuse of USTsites.

Regulations Pertaining to Underground Storage Tanks. Links to applicable sections of the Code of Federal Regulations.

Storage Tank State Resource Locator. Use this tool to locate state regulations and/or published guidelines for petroleum storage tanks.