House problems · Contaminated land · Sale and recourse
A lot cannot be seen at the visit, and it is the costliest latent defect there is. Here is how to check before buying, what the law requires, what the seller must say and what it costs.
A residential lot can be contaminated by a former oil tank that leaked, by a past activity on the lot or next door (garage, gas station, dry cleaner, workshop), by fill of doubtful origin or by migration of contaminants from a neighbouring site. The Environment Quality Act requires characterizing a lot when a designated industrial or commercial activity stops there (section 31.51) and publishing a contamination notice in the Land Register when regulatory thresholds are exceeded; it does not require the seller of a house to test their lot, but the Civil Code requires them to disclose what they know, and courts recognize soil contamination as a latent defect when the buyer could not see it. To find out: consult the index of immovables in the Land Register (contamination notices, servitudes), the ministry's directory of contaminated sites, the history of the lot (past uses, permits), and if needed commission an environmental site assessment: phase I (document research and visit, $1,500 to $3,500), phase II (boreholes and analyses, $5,000 to $15,000 and more). Decontaminating a residential lot runs from a few thousand to several tens of thousands of dollars depending on volume.
The buried or indoor oil tank that leaked (hydrocarbons), by far the most frequent case in pre-1980 neighbourhoods; a former use of the lot or the immediate neighbour (gas station, garage, dry cleaner, print shop, paint shop, neighbourhood dump); fill brought in at construction or landscaping (urban excavation soils, slag, residues); migration of a contaminated water table from a neighbouring site; pesticides and lead in old gardens and under old paints, rarely above thresholds. Contamination cannot be seen, except an oil smell in the basement, vegetation that will not grow, or a tank's fill pipes coming out of the ground.
The Environment Quality Act (EQA) imposes characterization on whoever permanently stops an industrial or commercial activity designated by regulation (section 31.51) and on whoever changes the use of such land; when analyses exceed limit values, a contamination notice is published in the Land Register and a rehabilitation plan must be approved before a new use. For a house, no law requires the seller to test, but article 1726 of the Civil Code warrants the buyer against latent defects, and courts have repeatedly held that contaminated soil the buyer could not detect is one, with damages that can include decontamination and loss of value. The seller who knows of a leak, an abandoned tank or an unfavourable analysis and stays silent is liable; one who sells "without legal warranty, at the buyer's risk" limits the recourse, unless they lied.
| Check | Where | Cost |
|---|---|---|
| Contamination notices, servitudes, former owners | Quebec Land Register (index of immovables) | A few dollars per document |
| Listed contaminated sites | Ministry of the Environment's directory of contaminated sites; federal open data for federal sites | Free |
| History of uses of the lot and surroundings | Roll, municipal permits, old fire insurance maps, aerial photos | Free to a few hundred dollars |
| Environmental site assessment, phase I | Environmental consultant (document research, visit, interviews) | $1,500 to $3,500 |
| Phase II assessment | Boreholes, soil and water samples, lab analyses | $5,000 to $15,000 and more |
On an ordinary house, phase I is only justified if the history or the inspection reveals a clue (tank, former business, fill). On a converted former commercial lot, a plex with a former corner store or a house with a buried tank, it is essential, and the lender may require it.
The Declarations by the seller form asks whether the seller is aware of contamination, tanks, leaks, environmental studies or notices. A seller who removed a buried tank with a clean analysis report discloses it and shows it: it is an asset. A seller who discovers contamination before the sale has three paths: decontaminate (excavation and disposal of soil, from a few thousand dollars for a small leak to several tens of thousands for a plume), sell while disclosing with an adjusted price and a report, or sell without legal warranty with full disclosure. The worst path is silence: the buyer often discovers the contamination digging for a pool, a drain or an extension, years later, and the recourse covers decontamination and loss of value. See also oil tank and sale.
Through the index of immovables in the Land Register (contamination notices), the ministry's directory of contaminated sites, the history of uses, and if needed a phase I then phase II environmental site assessment.
No, but they must disclose what they know (tank, leak, analysis, notice); hidden, known contaminated soil is a latent defect.
Yes, with disclosure, a report and a price that accounts for decontamination, or after rehabilitation; a notice in the Land Register follows the lot until the rehabilitation certificate.
The current owner toward the State; between seller and buyer, whoever hid the defect, through the warranty claim, or whoever accepted the risk by buying without legal warranty knowingly.
These problems are easier to settle before listing than after the buyer's inspection: see the pre-purchase inspection in Quebec, latent defects in Quebec and renovating before selling.
The Loaa & Manseur team, led by Lotfi Manseur and Loaa Al Daow, is the number 1 team at RE/MAX Platine in 2024 and 2025, 6th RE/MAX team in Quebec, 15th in Canada and in the global top 50 of large residential teams according to the official RE/MAX ranking, computed on actual transactions. Its Google profile counts 221 reviews with a 4.9 rating. Its offices are at 55 avenue de l'Équinoxe in Brossard, one bridge from the island, and every broker's licence can be checked in the OACIQ public register. Three things to verify yourself before calling us, and to demand of any other broker.
Also available in French: version française de ce guide.
Published September 7, 2026 by the Loaa & Manseur team, the number 1 team at RE/MAX Platine in 2024 and 2025, 6th RE/MAX team in Quebec, 15th in Canada and in the global top 50 according to the official RE/MAX ranking. Tell us about your project.
Quebec runs on civil law, so several French terms have no direct English equivalent: hypothèque is a hypothec and not a mortgage, vices cachés are latent defects, and the taxe de bienvenue is legally transfer duties. The full list is in our Quebec real estate glossary. See also this term explained.
Équipe no 1 de RE/MAX Platine en 2024 et en 2025, 6e au Québec, 15e au Canada et dans le top 50 mondial au classement officiel RE/MAX. Réponse en moins de 24 heures, sept jours sur sept.