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EPA's Report About Corrosion inside Underground Tank Systems Storing Diesel Fuel

Dear State UST Colleagues:

I am writing to notify you that EPA’s report, Investigation Of Corrosion-Influencing Factors In Underground Storage Tanks With Diesel Service, (EPA 510-R-16-001, July 2016) is now available. In addition to the report, EPA also developed a notice about corrosion risks in underground storage tanks (USTs) storing diesel fuel. I am requesting that you share our notice with the UST owners and operators in your state and any other stakeholders. Both the report and notice are available on EPA’s website at

In order to respond to concerns about reports of severe corrosion in USTs storing diesel fuel and better understand this phenomenon, EPA worked with industry and scientific experts to develop research. Our research showed that 83 percent – or 35 of 42 – of the USTs studied exhibited moderate or severe corrosion, but less than 25 percent of owners were aware of corrosion prior to an internal inspection. This corrosion could affect metal components inside both steel and fiberglass underground tank systems. Corrosion inside USTs can cause equipment failure by preventing proper operation of release detection and prevention equipment. If left unchecked, corrosion could cause UST system failures and releases, which could lead to groundwater contamination. 

Although we cannot project the actual percentage of USTs storing diesel fuel that are affected by corrosion nationwide, we think it is important to alert owners of USTs storing diesel about risks from corrosion. Our notice recommends owners check inside their tank systems and further investigate the condition of their diesel fuel tanks. 

In addition to states’ help with widely distributing to owners our notice about corrosion risks in USTs storing diesel fuel, UST industry associations are also helping us by sharing our notice with their members. Owners’ awareness and early actions could help protect owners from higher repair costs and help protect the environment from contamination from releases. 

Our next steps include our involvement in industry activities to evaluate the causes and resolve diesel storage tank corrosion issues. The Coordinating Research Council is organizing these activities. Industry is leading this effort; EPA is cooperating with and contributing to it. We are providing access to data and samples collected during our research, and we are participating in the research design. 

Thank you for your help in increasing awareness about corrosion in USTs storing diesel fuel. If you have questions about this, please contact Ryan Haerer ( or 202-564-0762) of my staff. 

Carolyn Hoskinson, Director

Office of Underground Storage Tanks 

U.S. Environmental Protection Agency