Connecticut Department of Energy and Environmental Protection

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Underground Storage Tanks (USTs) Serving Five or More Residential Units
Residential vs. Nonresidential
A “Residential underground heating oil storage tank system”, as defined by statute, heats "four (4) residential units or fewer”.  DEEP does not regulate residential heating oil USTs.
If an UST is used to heat five (5) or more residential units, that UST is “nonresidential”, even though people live there. 
Heating oil USTs under 2100 gallons
  • Construction: USTs and piping installed on or after October 1, 2003 must be double-walled.  They must use continuous interstitial monitoring to detect any release that may occur.  USTs must be fiberglass-reinforced plastic (FRP), cathodically protected steel or composite (fiberglass-clad steel).
  • Property Sales: Disclose all information about the UST (age, construction, location, etc.) to the buyer at least 15 days prior to closing.
  • UST failures (leaks from any part of the tank or piping) must be reported to DEEP immediately.
  • Clean up heating oil pollution promptly. 
Heating oil USTs 2100 gallons or larger
  • Construction: USTs and piping installed on or after October 1, 2003, must be double-walled.  They must use continuous interstitial monitoring to detect any release that my occur.  USTs must be fiberglass-reinforced plastic (FRP), cathodically protected steel or composite (fiberglass-clad steel).
  • Fee: There is a $100.00 per tank installation fee ($50.00 for municipalities).
  • Annual notification is required under Connecticut General Statute (CGS) section 22a-449(e).  Please note that heating oil tanks used for onsite heating are exempt from the annual fee at any volume.
  • Property Sales: Disclose all information about the UST (age, construction, location, etc.), including a copy of the annual notification, to the buyer at least 15 days prior to closing.
  • Life expectancy is the manufacturer’s warranty period.  FRP, cathodically protected steel, and composite USTs must be removed by the end of their warranty period, usually 30 years.  Unprotected steel USTs are beyond their life expectancy and must be removed.
  • System Testing:
    • FRP USTs are required to be tested 3 times:
      • 3-6 months after installation and
      • 2 years and 1 year before the end of life expectancy (usually at 28 and 29 years).
    • Cathodically protected steel and composite USTs are required to be tested twice:
      • 2 years and 1 year before the end of life expectancy (usually at 28 and 29 years).
  • Cathodic Protection Testing:
    • Cathodically protected steel USTs are required to be tested annually.
  • UST failures (leaks from any part of the tank or piping) must be reported to DEEP immediately.
  • Clean up heating oil pollution promptly.
For more information, contact the Storage Tank Enforcement Unit at (860) 424-3374 or deep.USTEnforcement@ct.gov.
Content last updated September 2019