an underground storage tank installation in a lined pit

An underground storage tank, also called a UST, is defined as a tank and any underground piping connected to the tank, that has at least 10 percent of its combined volume underground. In 1984, the federal Resource Conservation and Recovery Act established a regulatory program for USTs, found under RCRA Subtitle I. For information about what is happening at the national level, visit the U.S. Environmental Protection Agency's (EPA) Underground Storage Tanks (USTs) webpage. This particular website is a tremendous resource with federal regulations, frequently asked questions, information from all 50 states, technical bulletins and fact sheets.

Depending on what is or was stored in the UST and the USTs purpose, the UST may be regulated under Missouri's Underground and Petroleum Storage Tank Law, found in Missouri Revised Statues, sections 319.100 to 319.139, RSMo. The Underground Storage Tank Regulations are found in Code of State Regulations 10 CSR 26-2. The department's goal is to protect human health and the environment by building conditions under which good management of UST systems is common business practice. For information about financial responsibility requirements, visit Underground Storage Tank Financial Responsibility. For information about UST cleanup and closure, visit Regulated Storage Tank Cleanup and Closure

Note: The Missouri Department of Natural Resources does not regulate the operation of above ground storage tanks, also referred to as ASTs. For information about AST operation and inspection regulations, please contact the Missouri Department of Agriculture by telephone at 573-751-5636.


The department, tank owners and operators, installers, fuel suppliers and insurance providers all recognize that properly installing USTs, piping and monitoring systems is essential. The technical regulations regarding USTs can be found in Code of State Regulations 10 CSR 26-2. Before installing a new UST system, please be aware that vapor recovery requirements may also apply to your facility. Please visit the department's Vapor Recovery webpage to learn more about vapor recovery requirements in Missouri. If you have additional questions, please contact the department's Air Pollution Control Program

New Installation Requirements

Installers must: 

  • Have proof of financial responsibility on file. The Missouri Department of Agriculture requires all installers to be registered and provide proof of financial responsibility before installing a new UST system. For more information concerning this requirement, review the department's Financial Responsibility for Installers and Manufacturers of Underground Storage Tanks - PUB2423 fact sheet. You may also contact the Missouri Department of Agriculture, Weights, Measures and Consumer Protection Division, by telephone at 573-751-5636.
  • Notify the department at least 14 days before beginning an installation. The installer must complete and submit to the department, a Notification Installation of New Underground Storage Tank System MO 780-1949 form. New installation notifications expire after 180 days. 
  • Comply with PEI RP 100 or API RP 1615 and the manufacturer(s)’s installation guidance, practices and instructions.
  • Comply with all manufacturer certification or training requirements for equipment including, but not limited to, tank, piping, automatic tank gauge, line leak detector and interstitial sensors. 
  • Pre-test the tanks before installation, according to the manufacturer and PEI RP 100 or API RP 1615. 
  • Test the entire system (0.1 gallon/hour leak threshold) before bringing the system into use. 
  • Conduct an approved form of release detection if the tank is ballasted with product. Please note, you must install approved spill and overfill prevention equipment before receiving a fuel delivery.  Also, if you are in St. Louis City, St. Louis County, St. Charles County, Franklin County or Jefferson County, you must also install vapor recovery equipment before receiving the delivery. If ballasted with water, release detection is not necessary.

Additional Information

Please notify the department at least five days before work begins to install the UST system, in order to schedule the inspector's visit. In addition, please notify the department of any scheduling changes or delays. The purpose of these inspections is to not only confirm equipment installed, but to help identify and minimize any potential concerns before installation is complete. To schedule the inspection, please contact the department's installation inspection staff by telephone at 800-361-4827 or 573-522-5665, or by email at

The department has the authority to shut down an installation that is not being conducted according to the manufacturers’ written procedures or guidance, or does not comply with PEI RP 100 and API RP 1615. The shutdown may be restricted to the portion of the installation in question. The shutdown will be released upon approval by: a) the equipment manufacturer (if appropriate), b) the tank owner/operator or c) the department. 

All regulated USTs must be registered with the department. The owner of the new UST system must register no later than 30 days after bringing the tank into operation (dispensing fuel or using the product for its intended purpose). For more information about UST registration, visit Underground Storage Tanks Registration.


Missouri has a composite inspection program for underground storage tank inspections. The Missouri Department of Natural Resources and Petroleum Storage Tank Insurance Fund (PSTIF) have a joint contract inspection program, which consists of contract inspectors, department inspectors and compliance review staff.

The current contract inspector is Rounds and Associates. Their inspection manager is Mr. Brian Wiegert. He may be contacted at 855-808-8686.

All regulated facilities will be inspected at least once every three years, according to the requirements outlined in the federal Energy Policy Act. In addition to the required active and out-of-use facility inspections, department inspectors are inspecting new tank and piping installations. Inspectors may also investigate complaints and suspected releases.

The facility will receive a notification letter before a contract inspection. For non-PSTIF insured facilities, this notification will include a Request for Underground Storage Tank Records MO 780-1968 form. These records must be submitted to the department's Underground Storage Tanks Compliance and Enforcement Unit. If you have any questions, contact the department's Underground Storage Tanks Compliance and Enforcement Unit.


The department's main goal is to help facilities achieve and maintain compliance with the standards, laws and regulations concerning USTs. The department is responsible for new technology compliance evaluations, regulatory determinations and reviews. The department oversees the UST inspection program, reviews documentation to determine facility compliance with the laws and regulations and, if necessary, assists facilities in their efforts to return to compliance. The department also provides technical assistance to members of the regulated community, UST manufacturers and equipment providers, environmental consultants and any other parties that have questions concerning UST laws and regulations. For questions concerning regulatory interpretation or technical assistance, please contact the department's Tanks Compliance and Enforcement staff by telephone at 800-361-4827 or 573-522-5665, or by email at Information about proposed rule changes is available in the Regulatory Action Tracking System

  • Underground Petroleum Storage Tank Operational Compliance Fact Sheet PUB3079
  • If you would like to receive regular information and updates about environmental compliance issues, please click on the "Get Updates on this Issue" button to the right to subscribe to the department's Operational Tanks Assistance Bulletin electronic newsletter. The bulletin is directed towards those involved in properly maintaining, operating, testing and monitoring USTs and designed to keep all facilities informed so they can meet or exceed the environmental requirements. The bulletin provides clarification of regulatory requirements, information about upcoming changes or additions to federal or state regulations, commonly cited violations and other technical assistance. For information about other hazardous waste issues, visit the department's Hazardous Waste Compliance and Assistance webpage.

    Out of Use Tanks and Permanent Closure

    When a UST is out of use, it means the tank has been emptied so that no more than one inch of product remains, or that no more than 0.3 percent by weight of the total capacity remains. Once a tank is taken out of use, a site assessment must be conducted within 12 months. Tanks that remain out of use must be permanently closed within five years of being taken out of use (not associated with the date of the assessment). The regulations clarify all regulated tanks that have not been permanently closed, even those out of use before 1989, must still be permanently closed according to the regulations. For tanks out of use before Aug. 28, 1989, the person(s) who owned the tank immediately before it being taken out of use is the person(s) responsible for complying with the closure requirements. For information about how to perform a UST site assessment or closure, visit the department's Regulated Storage Tank Cleanup and Closure webpage.

    The cathodic protection system/ interior lining on an out of use tank does not have to be maintained after completing the site assessment. The tank owner/ operator has the following options for their out of use tank(s):

    • Stop maintaining and inspecting the cathodic protection system or interior lining. This is only recommended if the owner/ operator does not intend to ever use the tank again. 
    • Maintain the cathodic protection system or interior lining by conducting all scheduled inspections and associated repairs, ensuring the cathodic protection system is on, functioning and is being monitoring. 

    If an owner/ operator chooses option one but then opts to reopen the tank, the tank must pass a tank assessment/ tightness test. If the tank is steel:

    • Lining: The lining must either pass inspection or be repaired/ reinstalled
    • Cathodic Protection: The cathodic protection system must be redesigned or re-evaluated and re-energized by a cathodic protection expert