WA State Licensing: Underground storage tank

Underground storage tank

An Underground Storage Tank License is required for owners of storage tanks with all of the following:

  • Capacity greater than 110 gallons.
  • At least 10% of volume (including piping) below the surface of the ground.
  • Contain petroleum or other hazardous substances.

Note: Some tanks may be exempt.

How to get a license

  • The owner must file an application within 30 days after a new installation is complete, or upon modification or purchase of existing tanks.
  • A Notice of intent to install must also be filed directly with the Department of Ecology at least 30 days before new installation work begins.
  • All owners of regulated UST's, other than state or federal government agencies, must provide proof of ability to pay costs of a release from their tanks at the liability minimums set in WAC 173-360-400 through 406.

Note: If using insurance, attach a Certificate of Insurance from your provider, as set forth in WAC 173-360-480, listing as the certificate holder:

Business Licensing Service
PO Box 9034
Olympia WA 98507-9034

If you are not using liability insurance, attach a Certificate of Financial Responsibility as set forth in WAC 173-360-496.

Post your license

A license must be posted at each location where the licensee operates. You may not begin this business activity until you receive a Business License listing the required license.

Forms you’ll need


Specialty license Fee
Underground Storage Tank License $160 per tank
Weighing and measuring device Variable
Other fees that may apply Fee
State tax registration No fee
Registering your business name as a trade name $5
Business License Application fee $19 (non-refundable)

Contact information

State of Washington
Business Licensing Service
PO Box 9034
Olympia, WA 98507-9034

Phone: 1-800-451-7985
Email: BLS@dor.wa.gov
Fax: 360-705-6699

Office hours

Monday through Friday
8 a.m. to 5 p.m.

Mailing information

Please remember to enclose all necessary documents and fees with your completed application. Incomplete submissions will result in a delay in your licensure.

It is important that you contact our office, in writing, with any changes in address.

Regulatory questions

Department of Ecology
Phone: 360-407-7037 or 1-800-917-0043