How to protect your home from future flood damage

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Here comes the rain again.

Scientists have been warning us since that Eurythmics song came out in the early ’80s global warming would lead to more rain. In ensuing decades, studies and reports predicted with increasing clarity global warming would boost both the intensity and frequency of heavy rainfall events.

So when parts of Montreal were deluged with more than 100 millimetres of rain on July 10, and then another storm dumped about 150 mm only one month later, nobody in the climate science world was terribly surprised. This is the wettest summer on record since 1942, and the trend is to wetter.

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But thousands of homeowners across the province, many of whom had never experienced flooding before, faced a nasty surprise when their basements and garages took in water during those events. A flooded basement can be a financial and logistical nightmare because everything must be removed, cleaned and dried, or discarded. Soaked floors and wall boards must be removed within 48 hours to keep dangerous mould from growing. It’s a colossal mess that costs money, saps time and takes a toll on the psyche.

Some homeowners are blaming their municipalities and demanding improvements to the storm sewer network. But as Dorval Mayor Marc Doret told The Gazette this week, no city is in a position to rebuild its waterworks infrastructure before the next big storm hits.

“We can’t redo all the sewer networks in the city in the next year. Financially, it’s impossible,” he said “… And the question, when will the next big storm hit?” He notes Dorval has invested in storm retention basins and plans to do more for the hardest hit areas of his city, but it will take years.

Montreal has invested in 20 underground retention basins to hold massive amounts of water during heavy rains, but still, the city admits its sewer system can’t cope with these unprecedented storms. An additional $390 million will be spent over the next 10 years to update, repair and expand Montreal’s sewer system and the city is also exploring “green infrastructure” solutions, such as building parks and streets in ways designed to absorb runoff.

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But flood experts say municipalities need to get the message out to homeowners they can and should take action themselves, and now, to reduce the risk of flooded basements and to lesson the damage if water does get in.

Joanna Eyquem is managing director of climate resilient infrastructure at the Intact Centre, a research arm of the University of Waterloo. She lives in Montreal and also acts as the centre’s director for the Quebec region. It was founded in 2015 with a donation from the Intact Financial Corporation, a property and casualty insurance company, to develop guidelines to mitigate the effects of climate change and extreme weather.

The Intact Centre published a report in 2019 called Water on the Rise: Protecting Canadian Homes from The Growing Threat of Flooding. It reported basement flooding is on the rise across the country because of intense rainfall events, aging municipal infrastructure, loss of natural spaces, and lack of flood protection measures on the household level.

The report outlined the top 10 actions homeowners can take to reduce risk of basement flooding. Eyquem notes several of these actions can be completed by residents themselves, in less than a day, and for less than $500. The recommended actions include:

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• Remove debris from the nearest storm drain to your home
• Correct grading around your foundations so water runs away from the house, rather than toward it
• Clean eavestroughs and extend downspouts so run-off lands at least two metres from the house
• Install window wells and covers
• Keep floor drains clear
• Don’t store valuables in basement or put them in watertight containers stored off the floor
• Test sump pump and install back-up power in case of a power outage
• Install a backwater valve and clean it twice a year.

“One action that is completely free is to understand how the drainage in your own house works,” Eyquem said. “Do you have a sump pump, for example? Some people don’t even know they have one. Do you have a backwater valve? Some people don’t know where their floor drain is. It might be covered with carpet.”

The centre launched a residential flood risk reduction education program in 2016. They assessed 500 homes in Ontario and Saskatoon from 2017 to 2018 and identified the most common causes for flooding in private homes. They found:

• 85 per cent of the homes assessed had no backup sump pump or power source
• 71 per cent had furniture and electronics at risk of water damage
• 53 per cent of homeowners do not maintain their backwater valve
• 40 per cent of homeowners never maintain their sump pump
• 82 per cent had window wells with sides that were less than 10 cm above the ground
• 78 per cent had downspouts that deposited water less than two meters from the foundation
• 69 per cent had grading around their home that did not direct water away from the foundation
• 63 per cent had cracks or gaps in basement windows and frames

Eyquem commended Montreal’s new plan for flood resilience during heavy rains, but noted a big part of every city’s plan needs to be educating homeowners about what they can do to reduce their flood risk.

“I am quite happy to see the new strategy, (but) there is a big need for public education about a) what the risk is and b) what they can do to reduce the risk. Until something happens, a lot of people think it will never happen to them.”

mlalonde@postmedia.com

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