Many older homes — especially in Atlantic Canada, rural areas, and older Ontario/Quebec neighbourhoods — heat with oil stored in a tank, either aboveground (in the basement or beside the house) or in a buried underground storage tank (UST). Tanks corrode with age, and a leaking tank releases oil into the soil and groundwater.
Replace aboveground ~$2,500–5,000; a leak/contamination $10,000–100,000+Address before purchaseHeatingExterior
Why it matters
This is one of the few home issues that can become a very large environmental liability. A leak means soil and groundwater contamination, and the property owner is generally responsible for the cleanup — which can run from ten thousand to well over a hundred thousand dollars. Just as important: many insurers refuse to write or renew a policy on a home with an old or buried oil tank, or require it to be replaced or removed first, which can also affect your mortgage. Buried tanks are the bigger worry because they're hidden and hard to assess.
How to spot it
An oil tank in the basement or beside the house; fill and vent pipes poking out of the ground or an exterior wall (a sign of a possible buried tank, even if the visible tank is gone); oil staining or a petroleum smell. Ask the seller directly about the tank's age and type, and whether a buried tank was ever on the property and how it was removed — and get documentation.
What it costs
Replacing an aboveground tank runs roughly $2,500–5,000; removing or properly decommissioning a buried tank is $3,000–6,000+ if it's clean. But if the tank has leaked, environmental remediation can run $10,000–$100,000+ — which is exactly why this is a before-you-buy issue, not a later one.
What to do
Address before purchase. Confirm the tank's age, type, and insurability with your broker before you remove your conditions. For a buried or suspected buried tank, get a professional tank assessment or soil test rather than assuming it's fine. Budget accordingly and use any finding as a negotiation point — or make removal a condition of the sale. Use a licensed oil-tank or environmental professional.
Education and triage, not a home inspection. Casaroo flags signs of an oil tank — a basement tank, or fill and vent pipes — from photos; a licensed tank or environmental professional confirms its condition and whether any contamination exists. We flag; we don't inspect.
Common questions
What is Heating oil tanks?
Many older homes — especially in Atlantic Canada, rural areas, and older Ontario/Quebec neighbourhoods — heat with oil stored in a tank, either aboveground (in the basement or beside the house) or in a buried underground storage tank (UST). Tanks corrode with age, and a leaking tank releases oil into the soil and groundwater.
Why does it matter for home buyers?
This is one of the few home issues that can become a very large environmental liability. A leak means soil and groundwater contamination, and the property owner is generally responsible for the cleanup — which can run from ten thousand to well over a hundred thousand dollars. Just as important: many insurers refuse to write or renew a policy on a home with an old or buried oil tank, or require it to be replaced or removed first, which can also affect your mortgage. Buried tanks are the bigger worry because they're hidden and hard to assess.
How can I spot it?
An oil tank in the basement or beside the house; fill and vent pipes poking out of the ground or an exterior wall (a sign of a possible buried tank, even if the visible tank is gone); oil staining or a petroleum smell. Ask the seller directly about the tank's age and type, and whether a buried tank was ever on the property and how it was removed — and get documentation.
How much does it cost to fix?
Replacing an aboveground tank runs roughly $2,500–5,000; removing or properly decommissioning a buried tank is $3,000–6,000+ if it's clean. But if the tank has leaked, environmental remediation can run $10,000–$100,000+ — which is exactly why this is a before-you-buy issue, not a later one.
Last reviewed 2026-06-29.
This guide is general education, not a home inspection and not advice for your specific property — always
consult the appropriate licensed professional, and get a licensed home inspection before you remove conditions
or buy. Cost ranges are 2026 estimates that vary by region, size, and access; confirm specifics with a
qualified professional.