Who is responsible for the cost of removing an underground storage tank found on a property in Ontario?

The owner of the property at the time an underground storage tank and any associated contamination is found generally bears responsibility for dealing with it, since Ontario's environmental framework focuses on the current state of the land rather than only on who caused a problem. That means a buyer can end up responsible for removal and any related soil remediation even if a previous owner installed or abandoned the tank decades earlier.

Whether that cost can be shifted back to a seller depends on the facts: what the seller knew, whether the tank created a hazard the seller failed to disclose, and what representations, if any, were made in the purchase agreement about the property's condition and systems. This is why environmental due diligence matters most on properties with any history suggesting fuel storage, whether commercial, industrial, or an older home that may once have used oil heat. A buyer who has reason to suspect a tank might be present, from a home's age, a filled-in driveway patch, or an old vent pipe, should raise it before closing rather than after, since pre-closing negotiation over cost and responsibility is far more workable than a post-closing dispute.