Oil Tank Decommissioning


*Note: This is not a service that HAUS Inspection Services provides.
Please see the service providers listed below. 

Buried TankOil tanks don’t last forever. Decommissioning is the official process of ensuring that the existing tank is either removed or made inert. In most cases this requires a qualified professional to locate the tank, remove any oil, and fill the empty tank with slurry or foam. Once decommissioned, a decommissioning certificate is provided. Official decommissioning of oil tanks has been required since 1997. If no record of decommissioning is available, it is possible that it was done before then or that the previous tank was installed above ground and did not require decommissioning. For Seattle area homes, see the resources below to check if a record of decommissioning is available. Local oil providers like “Filco” or “Tanks by Dallas,” may also have their own records of decommissioning (see “Service Providers” below). A record of decommissioning certificates since 1997 is also kept by the fire marshal.



If an oil tank is buried on the property and has leaked, or begins to leak, environmental remediation is often required. Remediation usually requires permits and excavation of the old tank which can easily cost tens of thousands of dollars. A leaking tank can often be caught (as water in the fuel system) during regular servicing of the furnace. If an abandoned non-decommissioned tank is present you will want be absolutely sure the tank is decommissioned before closing. Keep in mind that evidence of a previous tank is very common and often identified during the inspection. In most cases the tank has been previously decommissioned.

Even if a home is supplied with natural gas, it’s important to know if heating oil was ever used. Your inspector can often find clues of a previously used tank such as remnant oil lines, breathers, or labeling.

If you own or consider buying a home supplied with oil heat, be sure to sign up for PLIA insurance. This free* insurance provided by Washington State covers cleanup expenses that may result from leaking tanks. See “Service Providers” below
*PLIA is funded by additional fees on heating oil purchases



Seattle Underground Storage Tank Records (click “VIEW DATA”):

Seattle area Fire Marshal’s office:
(206) 386-1450



Seattle Fire Marshal (decommissioning records since 1997)
(206) 386-1450

PLIA (Pollution Liability Insurance Agency)
(800) 822-3905

Filco (decommission, locate, soil test)
Seattle: (206) 547-8347
Tacoma: (253) 922-6383
Everett  (425) 257-0509

Tanks By Dallas (oil provider, furnace service, decommissioning)
(206) 365-0291

Sound Oil (oil provider, furnace service)
(206) 725-6300


Please note that the information and resources provided here are intended only as a courtesy by Wil Harnecker and HAUS Inspection Services, LLC.. This information is not intended for use in making real-estate or other financial or health related decisions. Further research and due diligence is always recommended during all steps of the home buying and selling processes.