Removing backyard oil tanks can cost homeowners hundreds of thousands of dollars, and one lawyer in the field says that could happen more often unless the government regulates the industry.

The City of Vancouver requires property owners to remove decades-old, potentially toxic tanks from their yards and clean up contaminated soil. In other municipalities, homeowners aren't required to remove the tanks, but many do because they're worried about declining property values or liability.

The undertaking can be a costly one. North Shore resident Susan Aldred received a bill for $224,000 after a contractor told her the contamination from an oil tank in her yard was so bad the entire lawn needed to be dug up.

She fought the bill in court, and it was lowered in a settlement deal. Aldred also sued the former owners of her home, forcing them to pay for it because she said they didn't disclose the presence of the tank.

Lawyer Jim Sullivan predicts there will be a lot more legal battles over who has to pay as long as the tank-removal industry is unregulated and anyone can perform the removal.

"I think this is an area that ought to be carefully scrutinized by the British Columbia government, that there is a real issue with regards to the companies that are doing remediation and whether or not they're living up to a standard," he said.

In Ontario, the business of removing the tanks has been regulated for a decade, and the job has to be done by a certified petroleum mechanic.

B.C. Environment Minister Terry Lake would not comment on regulating the industry here, but a ministry spokesman told CTV News in an email that homeowners should "undertake due diligence" when they select contractors.

"As part of the ministry's compliance strategy, the ministry has been following up with a number of contractors working in this sector," the email said.

"We are considering targeting training opportunities for contractors to ensure that they are aware of the legal requirements and management requirements."

The ministry also says it is "looking at ways to streamline the requirements for residential property owners."

But the email stressed that it is not considering implementing any more regulations for the tank-removal industry.

Removing oil tanks has brought in a lot of business for people like Martin Wouters of West Coast Tank Recovery.

"If there's a contaminated site, you can expect $20,000 to $30,000 as a minimum," he told CTV News.

But he said the industry has attracted a lot of "fly-by-night" companies, "people who don't know what they're doing."

The West Vancouver Fire Department issues permits for tank removals, and Asst. Chief Martin Ernst says he's seen what can go wrong when homeowners don't get independent advice from an environmental consultant.

"Removing oil tanks is serious business. It's not really a weekend job -- there are some checks and balances that need to be in place," he said.

"There are some excellent contractors working in the field, they're licensed, they have their WorkSafe BC coverage, they have experience. Others, fly-by-night, do not."

Experts suggest that if there's a risk of contamination, homeowners should hire an environmental engineer who doesn't work for the contractor to give objective advice.

For more on contamination from oil storage tanks, see the B.C. Ministry of Environment fact sheet.

With a report from CTV British Columbia's Mi-Jung Lee