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Unused Underground Residential Heating Oil Tanks (UURHOTS)

The Kirkland Fire Department is frequently asked questions by homeowners concerning the requirements for dealing with their unused underground residential heating oil tanks (UURHOTs) when they switch to another type of home heating. This information bulletin is provided to answer some of the most common questions and concerns regarding these tanks.

There are hundreds of UURHOTS in the City of Kirkland and many of them still contain heating oil. They are typically 200-300 gallons in size and are constructed of bare 12-gauge shell (about 1/8th inch thick - half the thickness of larger commercial tanks). The life of these tanks at best is about 30 years before corrosion makes them prone to leaking. Tanks this old should not be refilled with heating oil, and they should not be considered as usable for any future conversion back to oil heat.

The International Fire Code technically requires that any underground fuel tank which is unused for longer than one year be closed in a manner approved by the Fire Chief. This requirement has always applied to commercial tanks, such as are found at gas stations. Some jurisdictions also require a permit for abandonment or removal of tanks previously used to store fuel oil for residential heating tanks.

However, the City of Kirkland does not require a permit for these types of tanks, which are specifically excluded by in the Kirkland Municipal Code* from permit requirements (see below).

If you need additional information or assistance, please feel free to contact the Kirkland Fire Prevention Bureau at 425-587-3650.

*Kirkland Municipal Code, Title 21 Chapter 21.20.30, IFC Section 105.7.7 amended

Section 105.7.7 of the International Fire Code is amended to read as follows:


A construction permit is required:

1. To repair or modify a pipeline for the transportation of flammable or combustible liquids.

2. To install, construct or alter tank vehicles, equipment, tanks, plants, terminals, wells, fuel-dispensing stations, refineries, distilleries and similar facilities where flammable and combustible liquids are produced, processed, transported, stored, dispensed or used.

3. To install, alter, remove, abandon or otherwise dispose of a flammable or combustible liquid tank.

Exception: A permit is not required for the abandonment or removal of underground storage tanks previously used to store fuel oil for residential heating. It is the property owner’s responsibility to make the decision on how to proceed with abatement.


Fire Services
123 5th Avenue, Kirkland WA 98033

General Inquiries
T. 425.587.3650 | F. 425.587.3671