What are leaking underground storage tanks? An underground storage tank (UST) system is a tank or combination of tanks and connected underground piping having at least 10 percent of their combined volume underground. Federal UST regulations apply to UST systems storing either petroleum or certain hazardous substances. See EPA’s Learn About USTs webpage. EPA works with its state, territorial, Tribal, and industry partners to clean up releases from USTs to restore and protect groundwater resources and create a safe environment for those who live or work around these sites. See EPA’s Cleaning Up UST Releases webpage.

EPA provides support to Tribal governments to prevent and clean up petroleum releases from USTs. Basic information, training resources for Tribes, publications, and Tribal data can be found EPA’s UST Program in Indian Country.