Underground Storage Tanks

Leaking underground storage tanks (USTs) containing hazardous substances pose a threat to human health and the environment.

Leaking underground storage tanks (USTs) containing petroleum or other hazardous substances pose a threat to human health and the environment, as they can contaminate soil or groundwater, potentially contaminating drinking water aquifers.

The Washington State Department of Ecology (Ecology) regulates the installation, management, and monitoring of USTs to prevent releases to the environment per Chapter 173-360 of the Washington Administrative Code. Ecology publishes standards and requirements for installation, tank construction, tank testing, leak detection, spill containment and overfill protection. Ecology issues permits for tank operation and enforces the requirement that testing be done only by certified tank testers. Ecology also regulates the temporary and permanent closure and decommissioning of USTs.

What you need to know

USTs at the UW have been installed and are routinely maintained in accordance with Ecology regulations and guidance. However, if you are the owner or operator of an UST that you suspect or know has leaked, you are required to report the leak to EH&S immediately. We are required to report petroleum leaks within 24 hours of detection to Ecology. Ecology will require follow-up soil and groundwater investigation and/or cleanup if a leak has occurred.

What you can do to stay safe

Refer to the EH&S Design Guide on Underground Storage Tanks for more details and specifications for installing or decommissioning tanks.

Please contact EH&S at 206.616.0585 for assistance with UST requirements, such as required maintenance records, Ecology notifications, inspections and changes in tank use or content.


Services available

EH&S provides the following services:

  • Guidance on UST decommissioning, closures, temporary closures, and leaks

  • Ecology installation requirements, UST registrations, and Ecology compliance inspections

  • UST record-keeping requirements

Frequently asked questions

More Information


Environmental Programs Contact

(206) 616-5835
Reference Files