An oil tank in a Seattle home is one of the most common surprises in a northeast Seattle inspection, and one of the least understood. Most of the houses in Maple Leaf, Wedgwood, Ravenna and Pinehurst were built when oil was the ordinary way to heat a house, and a lot of them switched to gas or electric decades ago without ever taking the tank out of the yard. The tank is still there. So is the question of whether anyone dealt with it properly.

This page is the one place on our site that owns the oil tank question. Our inspection guides for Maple Leaf Craftsman homes, Ravenna Tudors and older homes and Pinehurst mid-century ramblers each flag the tank as one line on a longer list. Here we go through the whole thing: how to find out whether a house has one, what the Seattle Fire Department requires, what "decommissioned" does and does not tell you, what the seller disclosure asks, and what the state's heating oil program will and will not pay for. We are real estate brokers, not environmental consultants or attorneys. Everything below was checked at source on September 25, 2026, and anything involving soil, contamination or legal exposure goes to a licensed professional.

The short version

• Seattle requires a tank that has been out of service for a year or more to be decommissioned, either removed or filled in place, under Section 5704.2.13 of the Seattle Fire Code.

• The work needs a Seattle Fire Department permit before it starts (Permit Code 6103), and an ICC-certified decommissioner must be on site for the whole job. The Fire Department will not issue a permit after the fact.

• The Fire Department has no record of where tanks are. No permit was ever needed to install one. It only has records of decommissioning done under permit, from the late 1990s on for houses.

• "Decommissioned" is not the same as "clean." The Fire Code does not require soil samples, so a closed tank tells you nothing about whether it leaked.

• Washington's seller disclosure asks about fuel storage tanks directly, in the Environmental section of Form 17.

• The state's Heating Oil Loan and Grant Program can provide up to $75,000 per project, but it opens only twice a year and must approve work before it begins, which rarely fits a sale timeline.

Why an Oil Tank Sits Under So Many NE Seattle Homes

The housing stock tells the story. Pre-war Craftsman and Tudor blocks in Maple Leaf and Ravenna, and the post-war ramblers and split-levels in Pinehurst, Wedgwood and View Ridge, were largely built for oil heat. A delivery truck filled a tank through a pipe in the yard, and an oil furnace in the basement drew from it. When gas lines and heat pumps came along, the furnace got replaced. The tank, buried a few feet down beside the house, often did not.

The city's own records show the scale. The Seattle Fire Department publishes every residential heating oil tank decommissioning permit it has issued in an open dataset. We pulled it on September 25, 2026. In the two ZIP codes that cover most of our neighborhoods, 98115 and 98125, there are 9,130 residential decommissioning permits since 1996. They have never stopped coming:

• 1997 to 2000: roughly 260 to 420 permits a year across the two ZIPs.

• 2021 to 2025: still between 215 and 301 a year.

• 2026 through September 24: 167 permits, the most recent issued the day before we pulled the data.

• Tank size: the large majority of records list a 300-gallon tank, which is the standard residential size you should picture.

Two caveats. A ZIP code is a mail route, not a neighborhood, and both of these take in areas outside the ones we serve, so read those as ZIP totals. And the dataset only counts tanks someone decommissioned under permit. It cannot count the tanks nobody has found yet, which is the whole point of checking.

Buried Tanks vs Basement Tanks in a Seattle Home

Not every oil tank is underground. You will run into two kinds in northeast Seattle, and they are different problems.

• Underground tanks. The common case in older NE Seattle houses. Usually beside the house near the old furnace location, sometimes under a driveway, a patio or a later addition. You cannot see its condition, and a leak goes into the soil where nobody notices. This is the tank the Fire Department permit, the decommissioning rules and the state program are built around.

• Basement or indoor tanks. A steel tank standing in the basement or a crawlspace, visible and inspectable. Leaks show up as stains and smell rather than hiding in the ground. Taking one out is usually a smaller job, but ask the tank contractor whether a Fire Department permit applies to the specific work, rather than assuming it does not.

A house that is still heated with oil today is a third case. The tank is in service, so the decommissioning rule does not apply yet, but you are buying a heating system with a limited remaining life and a decision to make about what replaces it. Seattle's Office of Sustainability and Environment runs a Clean Heat program aimed at exactly that switch to a heat pump. Check its current terms directly before you count on it.

How to Check for an Oil Tank in a Seattle Home Before You Offer

There is no single registry that answers the question, so you build the answer from four places.

1. The Fire Department's decommissioning records

The Seattle Fire Department says plainly that it does not know where underground heating oil tanks are, because a permit was never required to install one. What it has are records of tanks removed or decommissioned under permit after 1997 for residential properties. Before that, no permit was required. Those residential records are searchable online in the City's open data portal under "Underground Storage Tank (UST) Records - Residential," by address. Older or missing records can be requested through the City's public records request center.

How to read the result:

• A record with a date, a method and a company: good. Ask the seller for the paperwork behind it (more on that below).

• A record with incomplete tank information: the City's own dataset notes say this means the required follow-up report never reached the Fire Department. Ask why.

• No record: means nothing on its own. It could be a house that was always on gas, a tank closed before permits were required, or a tank nobody has found.

2. What the house itself shows you

Walk the outside of the house and the basement before you write. The tells are a capped fill pipe or a vent pipe sticking out of the ground or up the side of the house, small copper or steel lines coming through the foundation wall, a patched hole in the basement wall where those lines used to enter, or an old oil furnace or a chimney that served one. A heating conversion with no tank paperwork is the pattern to watch for.

3. The seller disclosure

Washington's Form 17 asks the seller directly (section 7E below). Read the answer and any attached explanation. "Don't know" is a legal answer, and in an estate sale or a long-held rental it is common. It is also a reason to do the next step.

4. A tank sweep

A tank sweep, also called a tank locate, is a scan of the yard by a tank service company, typically with metal-detecting equipment plus probing where the scan hits something. It is how you find a tank nobody documented. What it does not do is test soil. If a sweep finds a tank, whether it leaked is a separate question answered by sampling, done by an environmental professional. We order a sweep on any older NE Seattle house where the heating history is not documented. Get quotes from licensed tank service companies; the Washington Department of Ecology keeps a list of registered tank service providers.

Shopping the older blocks of Maple Leaf, Wedgwood, Ravenna or Pinehurst? Browse current NE Seattle listings and look at the year built before the photos. Anything built before the 1970s gets the oil tank question from us, every time.

Oil Tank Decommissioning in a Seattle Home: What the Fire Code Requires

The Seattle Fire Department's Client Assistance Memo 5962, updated March 2024, lays out the rules. In summary:

• The trigger. Section 5704.2.13 of the 2021 Seattle Fire Code requires a residential heating oil tank that has been out of service for a year or more to be decommissioned, along with its connected piping.

• The permit. Section 105.5.20 requires a permit to remove, abandon, place temporarily out of service or otherwise dispose of a heating oil tank. For each underground residential tank, that is Permit Code 6103, Residential Heating Oil Tank Decommissioning.

• Who gets it. The permit is issued to whoever is doing the work, not to the homeowner, unless the homeowner is a certified decommissioner doing the work.

• Timing. Work may not start until the applicant has a permit application stamped "Approved to Proceed." The Fire Department states it will not issue a permit after decommissioning work has been performed.

• Who does it. The work must be performed, or directly supervised, by an individual certified by the International Code Council as an underground storage tank decommissioner, with a current certificate on file with the Fire Department. That person must be at the tank for the entire operation, whether the tank is being removed or filled in place.

• The report. The certified decommissioner completes the Fire Department's Heating Oil Tank Decommissioning Report Form and returns it within 30 days of finishing, and must give the property owner a copy within the same 30 days.

The permit fee is set in the City's fire code fee schedule. Your contractor pulls the permit, so it will show up on their bid.

Removal vs Fill in Place for an Oil Tank at a Seattle Home

The Fire Code allows two methods, and it treats them as equal for its purposes. They are not equal for a future buyer.

• Abandon in place. The oil and bottom sludge are pumped out, the inside is triple rinsed, and the tank is filled with an inert solid such as sand, concrete slurry or foam. The fill pipe is cut and capped. The tank stays in the ground.

• Removal. The tank is dug up and hauled away, and the hole is backfilled. Removal exposes the soil under the tank, which is the moment anyone can actually see whether it leaked.

Filling in place is by far the more common choice here. In the Fire Department's records for 98115 and 98125 since 1996, about seven in ten decommissioning permits were abandonment in place and roughly a quarter were removals. Among the records since 2021 that list a method, it is still about seven in ten (877 filled in place, 325 removed). Three sentences in the Fire Department's own memo are worth knowing before you choose, or before you accept a seller's choice:

1. Tanks suspected of leaking should be removed from the ground rather than abandoned in place.

2. The Fire Department cannot predict what future regulations may require of tanks abandoned in place under current guidelines, and a tank abandoned in place now may later require removal at additional cost.

3. Compliance with the Fire Code does not require a site plan or any soil samples.

That third point is the one buyers miss. A Fire Department permit and a decommissioning report prove the tank was closed by a certified person. They say nothing about the soil. If you want to know whether it leaked, that takes sampling.

The Paperwork That Should Come With an Oil Tank in a Seattle Home

When a seller says "the tank was decommissioned," this is what we ask for. The Fire Department's memo tells owners to keep most of it, so a careful seller will have it.

• The permit application stamped "Approved to Proceed." The contractor is required to give the owner a copy.

• The Heating Oil Tank Decommissioning Report Form, completed by the ICC-certified decommissioner. This should show the tank size, the method and the fill material.

• Receipts, certifications and photos from the job.

• Soil sample results, if any were taken. Not required by the Fire Code, so often there are none.

• A No Further Action letter, if a leak was found and cleaned up through the state's Technical Assistance Program. The state agency that issues it notes that it may be helpful with future property transfers, which is exactly the use you have for it.

A decommissioning with a permit, a report and no soil data is a normal NE Seattle file. A heating conversion with no tank record and no sweep is the file we would slow down on.

If the Oil Tank at a Seattle Home Has Leaked

The City's guidance is short: if you discover or suspect a leak, report it within 24 hours to 1-800-OILS-911 and stop any automatic heating oil deliveries. The Fire Department also notes that the Washington Department of Ecology has reporting requirements depending on the extent of contamination, and that those obligations sit outside the Fire Code. Have a leaking tank emptied right away so the contamination does not spread.

Stopping deliveries sounds obvious. It is on the list because oil companies on automatic delivery have filled tanks that were no longer connected to anything. If you buy a house that used to be on oil, make sure no delivery account is still attached to the address.

From there, the scope, the sampling and the cleanup belong to an environmental consultant. What a buyer or seller controls is the timing, which is where the state program comes in.

Washington's Heating Oil Loan and Grant Program

The Washington State Pollution Liability Insurance Agency (PLIA) completed the move of its old Heating Oil Insurance Program into the Heating Oil Loan and Grant Program on July 1, 2025. As published on PLIA's program page and its July 2026 program guidance:

• Total per project: up to $75,000, grants and loans combined.

• Preliminary Planning Assessment grant: up to $7,000 for a PLIA-contracted environmental consultant to find out whether there is contamination, how much, and what cleanup, removal or upgrades would cost.

• Technical Assistance Program fee grant: covers the $1,500 enrollment fee, only if contamination above state cleanup levels is found.

• Cleanup grant: up to $60,000 per applicant for a single heating oil tank, for cleanup costs and associated tank removal. It cannot be used to decommission a tank in place or for infrastructure upgrades.

• Loans: up to $68,000 without a cleanup grant, usable for decommissioning in place, cleanup the grant does not cover, or replacing the heating system, including a heat pump. Terms of 10, 20 or 30 years at the prime rate as of March 1 of the year you apply, with a possible 0.5 percent reduction for energy-efficient equipment, and no prepayment penalty. Loan approval includes a financial review by the Department of Health.

• Eligibility: you must own the property where the tank is, and either need to clean up a leak or, with no leak, want to take the tank out or change your heat source. It is not limited to low-income households.

Now the part that matters for a sale. Application cycles open twice a year, in May-June and November-December, and each stays open for 45 days. PLIA must pre-approve all work before it starts, and it cannot reimburse work already completed. As of this writing PLIA's own page also warns of longer than normal processing times. Put that against a typical 30-to-45-day escrow and you can see the problem. This is a program for an owner planning ahead, not a tool you can pull into a transaction that is already under contract. A seller who is a year or two from listing and knows there is a tank has the right timeline to use it. A seller listing next month usually does not.

Buying a Seattle Home With an Oil Tank: How We Handle It

We do not tell buyers to walk away from houses with tanks. There would be very few older NE Seattle houses left. We tell them to know which of these situations they are in, and to price it.

• Decommissioned under permit, paperwork in hand. Usually fine. If it was filled in place with no soil data, decide whether that is a risk you can live with or whether you want sampling during your inspection period.

• Decommissioned before permits were required, or with no paperwork. Treat it as undocumented. Sweep, and consider sampling.

• Tank found, never decommissioned, no sign of a leak. The common negotiation. The usual paths are the seller decommissioning it under permit before closing, or a credit so you can do it yourself afterward. If the seller does the work, ask for removal rather than fill in place if you care about seeing the soil, and make sure the permit is pulled before the work, not after.

• Evidence of a leak. Stop and bring in an environmental consultant before your contingency runs out. The cost range just widened past what an inspection period can price.

Two questions are not ours to answer. Whether your lender will want anything on the tank, ask your mortgage advisor. Whether your homeowner's policy covers anything related to an old tank, ask your insurance agent, before you remove your inspection contingency.

Selling a Seattle Home With an Oil Tank: Disclosure and Prep

Washington's statutory seller disclosure statement is set out at RCW 64.06.020, and the tank question is not buried. Section 7, Environmental, question E reads: "Are there any substances, materials, or products in or on the property that may be environmental concerns, such as asbestos, formaldehyde, radon gas, lead-based paint, fuel or chemical storage tanks, or contaminated soil or water?" It is a starred question, meaning a "yes" needs a written explanation. Question 7G separately asks whether there is any soil or groundwater contamination. (Section 5B also mentions tanks, but that line asks whether a tank included with the sale is leased, which is usually about propane, not an old oil tank.) The statute was amended in 2026 with a new version of the form taking effect January 1, 2027; the fuel storage tank question reads the same in both.

The form states the seller is disclosing based on actual knowledge, and that it is not a warranty. If you know there is a tank, including one filled in place years ago, our practice is to say so and attach the paperwork. If you are unsure how to answer for your situation, that is a question for a real estate attorney, not for us.

On the prep side, a known tank is much cheaper to handle before you list than during a buyer's inspection period. Before listing, you can get multiple bids, choose the method, and hand buyers a finished file. During escrow, you get one bid, a deadline, and a buyer imagining the worst. Our pre-listing repairs guide puts the tank on the short list of repairs that change what a buyer is willing to offer, and this is why.

Who Should Not Buy a House With an Undocumented Oil Tank

We would rather talk you out of a house than into one, so here it is. If your budget has no room for a contaminated-soil surprise after closing, do not waive your inspection contingency on a pre-1970s house with an undocumented heating history, however competitive the offer review is. If a seller will not allow a sweep, that tells you something. And if the tank turns out to have leaked and the seller will not deal with it or price it, walk. Older NE Seattle houses come back to market every week, and the next one may have a clean file.

Looking at an older NE Seattle house with a heating history nobody can explain? Reach out through our contact page. We will pull the Fire Department record with you, read the disclosure, and tell you plainly whether the tank is a negotiating point or a reason to keep looking.

Frequently Asked Questions About an Oil Tank in a Seattle Home

How do I find out if a Seattle home has an oil tank?

Start with the Seattle Fire Department's residential Underground Storage Tank records on the City's open data portal, searchable by address. They cover tanks decommissioned under permit, which for houses means after 1997. The Fire Department has no record of where tanks were installed, because installing one never required a permit. Then read the seller's Form 17 disclosure, look for a fill pipe, vent pipe or old oil lines at the foundation, and order a tank sweep from a tank service company if the heating history is undocumented.

Does Seattle require an old oil tank to be removed?

Not removed, but decommissioned. Section 5704.2.13 of the Seattle Fire Code requires a heating oil tank that has been out of service for a year or more to be decommissioned, either by removal or by abandonment in place, which means cleaning it out and filling it with an inert solid such as sand, concrete slurry or foam. A Fire Department permit (Code 6103) is required before the work starts, and an ICC-certified decommissioner must be on site for the whole job.

Is it better to remove an oil tank or fill it in place?

The Seattle Fire Code accepts both. Removal lets everyone see the soil under the tank, and the Fire Department says tanks suspected of leaking should be removed rather than abandoned in place. It also says it cannot predict what future rules may require of tanks abandoned in place. Filling in place is the more common choice in NE Seattle and usually the less disruptive one. Ask a licensed tank contractor to price both for your lot.

Does a decommissioned oil tank mean the soil is clean?

No. The Seattle Fire Department states that complying with the Fire Code does not require a site plan or any soil samples. A permit and a decommissioning report prove the tank was closed by a certified person, not that it never leaked. If you want to know about the soil, that takes sampling by an environmental professional, and a No Further Action letter from the state if a leak was cleaned up.

Do Washington sellers have to disclose an oil tank?

The statutory seller disclosure statement in RCW 64.06.020 asks it directly. Section 7E asks whether there are substances or products on the property that may be environmental concerns, naming fuel or chemical storage tanks, and a yes requires an explanation. The seller answers based on actual knowledge, and the form is not a warranty. How to answer for a specific property is a question for a real estate attorney.

Will the state pay to deal with an oil tank?

Possibly, on its own schedule. The Pollution Liability Insurance Agency's Heating Oil Loan and Grant Program provides up to $75,000 per project, including a planning assessment grant of up to $7,000, a cleanup grant of up to $60,000 for a leaking tank, and loans at the prime rate for decommissioning or a new heat source. Applications open only twice a year, in May-June and November-December, and PLIA must approve work before it begins, so it rarely fits inside a home sale already under contract.

A note on sources. The rules on this page were checked on September 25, 2026 against the Seattle Fire Department's Client Assistance Memo 5962, Decommissioning of Residential Heating Oil Tanks (updated March 2024) and its permits guidance; the City of Seattle's residential heating oil tank decommissioning flyer; the Seattle Fire Department's Underground Storage Tank (UST) Records - Residential dataset on the City's open data portal (queried September 25, 2026, records through September 24, 2026); RCW 64.06.020 as published by the Washington State Legislature, in both the current version and the version effective January 1, 2027; and the Washington State Pollution Liability Insurance Agency's Heating Oil Loan and Grant Program page, its July 2026 program guidance and its program FAQ. Program terms, fees and application windows change. Confirm them with the agency before you rely on them.

More northeast Seattle reading: What to inspect in a Pinehurst mid-century rambler · What to inspect in a Ravenna Tudor or Craftsman · Pre-listing repairs in NE Seattle that pay back