U.S. Environmental Protection Agency
Office of Underground Storage Tanks
Washington, D.C.
www.epa.gov/ust
January 2020

E15's Compatibility With UST Systems

The environmentally safe growth of fuel containing 15 percent ethanol (E15) markets depends
on E15 being stored and dispensed from underground storage tank (UST) systems that are
compatible with E15. Storing and dispensing E15 at gas stations with equipment that is not
compatible with higher blends of ethanol fuel can result in leaks and releases that contaminate
land and groundwater. Most older and even some newer existing UST systems (which includes
but is not limited to tanks, pumps, ancillary equipment, lines, gaskets, and sealants) are not
fully compatible with E15 and require modification before storing E15. For example, the actual
tank is often compatible with E15, but some of the connectors and pump components may not
be. That can lead to leaks. Dispensers are not part of the UST system, by definition, but face the
same compatibility concerns and are a critical part of the fueling system for our constituents.

In June 2019, EPA issued Modifications to Fuel Regulations to Provide Flexibility for E15;
Modifications to RFS RIN Market Regulations, which removes barriers to E15 year-round use.
This final rule means more people might choose to offer E15 at gas stations and other fueling
facilities.

Since 1988, EPA's UST regulations require fuel to be stored in systems that are compatible with
the type of fuel being stored. Limited use of ethanol started in some parts of the United States
in the late 1970s, with nationwide ethanol use beginning in the mid-2000s. Decades ago
organizations, such as Underwriters Laboratories (UL), first designed and tested some UST
system components—such as tanks and piping—to be compatible with E10. Most tanks and
piping are now only available in 100 percent ethanol compatible options. But most other
equipment was not tested for E15 or higher blends. Increasing the amount of ethanol from 10
percent to 15 percent in fuel can make a significant difference in materials' compatibility with
many UST system components over the life of the UST system.

EPA's UST program provides helpful information about E15 and other emerging fuels on our
website at www.epa.gov/ust. We continue to work cooperatively with states, industry,
equipment manufacturers, and service providers on research about compatibility, corrosion
and degredation concerns, and potential solutions. EPA will also continue our partnership with
industry, states, and tribes to facilitate information sharing, guidance, and compliance with E15
compatibility requirements.


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