Before natural gas became common, many Lower Mainland houses were heated with oil. A furnace in the basement burned fuel oil, and the oil was stored in a tank. Some tanks sat in the basement. Some were buried in the yard. When the houses switched to gas, some tanks were removed. Many were not.
If you are looking at a house built before the 1970s, an oil tank is a reasonable question. It is a small chance on any one house, and a very expensive problem when it does exist.
Why it matters
A buried steel tank corrodes over decades. If it leaks, the oil goes into the soil, and in some cases the water table or a neighbour's property. Cleaning up contaminated soil can be costly, and it can involve environmental consultants, excavation and testing. Even a tank that has not leaked can complicate a sale: lenders, insurers and buyers may want evidence that it was dealt with.
A tank inside the house is a smaller concern, but it can leak onto the floor and cause odour and damage, and old basement tanks are a fire safety item.
Clues an inspector can see
A visual inspection cannot find a tank in the ground. What it can do is look for signs that one was or is present.
- Fill pipe and vent pipe. Near the foundation, often on the side wall, you may see one or two short pipes poking out of the ground or up the wall, sometimes capped. One is the fill pipe and one is the vent.
- Copper tubing. A small copper line that runs from the ground or through a wall, into the basement, may have fed oil to a furnace.
- Old furnace. An oil-fired furnace or burner, or the remains of one, or a chimney flue that is lined for it.
- Patches. A section of concrete or a wall patched in a spot where a fill line went through.
- Soil. A bare, unusual patch in the lawn, or staining or odour near the foundation.
- Basement tanks. Large cylindrical steel tanks on legs, often with a gauge, may still be in a corner or a utility room.
None of these is proof. A fill pipe may have been left after a tank was removed, and a missing pipe does not prove there is no tank. The honest answer from an inspection is often "we see signs consistent with a past oil system, and we cannot say what is underground."
What can be done
If there are signs, the usual next steps:
- Ask the seller. Ask directly whether there is or was an oil tank, and ask for records of removal. A removal record from a qualified contractor, with soil test results, is the document you want.
- Ask about the neighbours and the history. Some older neighbourhoods had many oil heated houses. Realtors and neighbours may know.
- Hire a locator. Specialists use metal detectors, magnetometers or ground-penetrating radar to find buried tanks. This is not part of a home inspection and is booked separately.
- Ask a contractor about removal or decommissioning. An abandoned tank may be removed, or sometimes cleaned and filled in place. Soil testing follows. A qualified contractor can say what is appropriate on your lot.
- Check with your insurer and lender. Some will ask for documents, and some will not cover a property with an active or unremoved tank.
Each of these steps takes time, and a short subject period can make them hard. If there are signs of a tank, tell your realtor early and ask for an extension.
What an inspection report will say
Where we see an oil furnace, a tank, a fill pipe or a vent pipe, the report will describe it and recommend further investigation. If the tank is in the basement we note its condition, any leaks or corrosion, and the piping. We do not inspect the inside of the tank, and we do not test soil.
If you already own the house
If you own an older house and find signs of a tank, you have time. Find the records. If none exist, a locator is the first step. If a tank is found and has not leaked, removal and a clean soil test is a good thing to have on paper for the day you sell.
If you smell oil, see staining near the foundation or find oil in a drain or a sump, treat it as urgent and call a qualified environmental contractor.
If you are selling
Have the records ready. If the tank was removed years ago, find the removal certificate and soil results. If you cannot find them, a locator scan and a written statement can help a buyer. A pre-listing inspection can tell you whether there are visible clues before a buyer does. See pre-listing inspections.
In short
Oil tanks are a legacy of the heating technology that came before gas. They are not common in newer houses and not unusual in older ones. A home inspection can point out the signs. Only a locator and a qualified contractor can say what is under the ground, and paperwork from a past removal is the best evidence you can have.