Sump pumps, flood maps: How to assess climate risks when house shopping

Neighbours deal with the flooding on Cordella Avenue after a severe thunderstorm caused localized flooding in Toronto on Wednesday, July 8, 2020. THE CANADIAN PRESS/Carlos Osorio

TORONTO — When Kathryn Bakos was house hunting a few years ago, her checklist included some things that might not come first in mind for a dream home.

“I did not want a reverse-sloped driveway,” she explained in an interview.

“My husband said, well, what happens if we find our perfect home? I said, it’s not our perfect home if it has a reverse slope.”

Such driveways direct water toward the home, an issue Bakos is well aware of after researching how increasingly common catastrophic floods hurt home values.

The angle of a driveway is just one of many hazards home shoppers need to understand as climate change creates more extreme weather trends, said Bakos, managing director of finance and resilience at University of Waterloo’s Intact Centre on Climate Adaptation.

And while figuring out the level of risk any home faces isn’t an easy task, she said it’s important to remember that no one is completely immune.

“If you live anywhere that it rains, you’re at risk of flooding.”

The need to understand the threats is growing along with the damages. The past decade saw $37 billion in total insured losses from catastrophic weather, nearly triple the previous decade, according to the Insurance Bureau of Canada.

Assessing risks can start with the property itself -- looking for grading and where water will flow, along with what kind of protections the house has against that water. Features like a backflow valve that blocks overflowing sewer systems, a sump pump to get water out, and an alarm system to warn water is in the basement are becoming increasingly important, said Bakos.

Checking on the chances of a potential flood or wildfire in an area is less straightforward, said Chris Chopik, a realtor at Sotheby’s. Flood risk mapping in Canada is often fragmented, outdated and can be hard to interpret, he said.

“In every jurisdiction, you’re going to have a different landscape, because there’s no, sort of, universal, one window access to the information.”

The federal government has been working to update the flood mapping system, with an expected $220 million spent between 2021 and 2028, but it’s not clear when the public might have full access to the data.

Natural Resources Canada also wants to develop a national approach to home labelling, which would create standard information for energy performance and climate resiliency, but it’s still in the consultation phase.

For now, there’s a patchwork of systems, like flood plain maps produced by Ontario Conservation Authorities and cities like Calgary, as well as maps that cover a wider range of hazards, like PEI’s Climate Hazard & Risk Information System.

The challenges of interpreting some of the maps and data mean it can be a good idea to seek out experts who have deeper knowledge of the risks, said Chopik.

“It would always be my advice to engage a real estate professional who has good answers to questions that you’re curious about.”

Private services are also trying to fill some of the gaps.

Noah Intelligence Inc. has set a goal to ultimately map the flood risk of every home in Canada, but has set a target for all of Toronto by the end of March.

The company’s approach includes going beyond flood plain mapping to look at how stormwater systems react to high water flows, which lead to the flooded basements that cause much of the damage.

“The vast majority of that flooding comes from inadequate stormwater management systems. They weren’t built for today’s extreme rainfall,” said Chris Godsall, who co-founded the company with Steve Van Haren.

He pointed to the July 2024 flash floods in Toronto and southern Ontario that caused about a billion dollars of insured damage as an example.

“That wasn’t a climate catastrophe. It wasn’t a hurricane. It wasn’t a hailstorm. It was just a lot of rain that overwhelmed the stormwater system.”

Godsall said the plan is to provide some level of flood data for homes for free, and charge a small fee for greater detail.

Canadian real estate listing companies have generally not yet started including climate data because sources remain a challenge.

“There is no agreed upon mapping of climate risk in Canada, meaning we can’t access data that would permit displaying alongside property listings,” said Pierre Leduc, spokesperson for the Canadian Real Estate Association which owns Realtor.ca.

But buyers are paying more attention to extreme weather, said Katie Sanga, a sales representative at Re/Max Professionals North in Huntsville, Ont.

“They’re definitely more cautious, and more aware of what’s going on in the area for climate risks,” said Sanga, noting two major floods in the Muskoka region in the last decade have helped raise awareness.

“Buyers look at the long-term view now, as opposed to just looking at what’s happened in the most recent years.”

Rural properties can raise more subtle risks, like shoreline erosion as the spring runoff gets more intense, said Sanga. Natural vegetation helps dampen the problem, she said.

For buyers, it’s also important not only to assess the risks of the property, but to check in on factors like insurance, especially if there’s risk of flooding, she said.

“I would definitely suggest doing a condition based on getting adequate insurance for the property.”

Overall, the shifting risk factors and variety of data sources means homebuyers have to make sure they both do their research, and check in with experts, said Sanga.

“The biggest thing is to do your homework.”

This report by The Canadian Press was first published Jan. 29, 2026.

Ian Bickis, The Canadian Press