Flooding: Causes, Impact, and How to Stay Safe
On July 16, 2024, a series of severe thunderstorms dropped close to 100 millimetres of rain on Toronto in just over three hours. The city's drainage system couldn't keep up. The Don Valley Parkway and Gardiner Expressway disappeared under water, Union Station flooded badly enough to disrupt subway and regional train service, and roughly 167,000 people lost power as the storm rolled through. By the time it was over, the damage came to an estimated $940 million in insured losses, thus ranking as one of the costliest natural disasters in Canadian history.
The Toronto storm was a stark reminder that flooding can happen with little warning and affect far more than homes and streets. It can interfere with transportation, damage infrastructure, knock out essential services, and leave communities in recovery for months. This article covers what causes flooding, the different forms it can take, the toll it takes on people and communities, and what you can actually do about it, before, during, and after the water rises.
What is Flooding?
Essentially, flooding is the occurrence of water over an area of normally dry land. The water may only be a few inches deep, or deep enough to fully submerge a house. Flooding occurs when rivers overflow, heavy rain overwhelms drainage systems, snow melts rapidly, or coastal waters move inland. Some floods develop slowly over several days or weeks, while flash floods can develop within minutes.
When floodwater reaches transformers, substations, or underground lines, utilities often have to cut power for safety, even in homes that weren't directly flooded. That's a problem if you're relying on a sump pump to keep water out of your basement, or if someone in the house depends on medical equipment that needs to stay plugged in.
It's part of why most homeowners now treat whole-home backup, such as the EcoFlow DELTA Pro Ultra, less of a luxury and more of an essential part of flood preparedness. Its output goes up to 21.6 kW, enough to run a whole house including central air conditioning, and depending on the setup, it can hold enough capacity to keep your home backed up for weeks.
What Causes Flooding?
Water doesn't need much of an excuse to end up where it shouldn't. Usually it's a combination of weather patterns, geography, and how the land has been built up that decides whether a storm turns into a flood.
Rain that outpaces the ground's capacity: Soil can only soak up water so fast. Once a storm delivers more than the ground can handle, whether in one intense burst or over several straight days, the extra water has nowhere to go but across the surface.
A fast spring thaw: When a heavy winter gives way to a sudden warm-up, melting snow can pour into rivers and streams faster than they're built to handle, and ground that's still partly frozen underneath only makes the runoff worse.
Storms driving seawater onto land: Coastal storms can push ocean water well past the shoreline, and if that surge lines up with a high tide, the flooding gets significantly worse.
A dam or levee giving out: These structures are designed to hold water back, so when one fails, everything behind it moves downstream fast, often with almost no warning.
Cities built to shed water, not absorb it: Pavement, rooftops, and parking lots send rain running off instead of soaking it in, and a lot of storm sewer systems were designed for rainfall patterns that no longer match what actually falls today.
Types of Flooding
Not all floods behave in the same way. Understanding the kind of flooding that could occur in your community can make it easier for you to recognize the danger and respond appropriately.
Flash floods: They are the most dangerous type of flood because of how fast they occur. Intense rainfall can turn a dry street into a fast-moving hazard within minutes, often before there's time to issue a warning. Urban areas are particularly exposed since traditional impermeable pavement doesn't absorb water, but dry, compacted rural soil can fail just as badly.
River and overland floods: These build more gradually, often over several days, as rainfall or snowmelt pushes water levels past what a riverbank or drainage system can hold. Most river floods give some advance warning, though a dam or dike failure can still turn a predictable flood into a sudden one.
Coastal flooding: Coastal flooding is driven by storm surge, high winds, high tides, and rising sea levels along Canada's coastlines. Several of these factors often combine at once, and low-lying coastal areas with fewer natural defences tend to see the worst of it.
The Impact of Flooding
The effects of flooding can extend far beyond wet floors and damaged belongings. In severe events, the consequences can affect health, safety, housing, businesses and entire communities.
In the moment, the biggest danger is the water itself. It can carry debris, hide sinkholes or missing manhole covers, and turn deadly if it reaches wiring or downed power lines. Even water that looks shallow and calm can knock a person off their feet or sweep a car off the road, which is exactly why citizens are warned against walking or driving through it.
Once the water recedes, the health risks start. Floodwater often mixes with sewage, chemicals, or bacteria, so anyone who comes into contact with it faces a real risk of illness. Mould moves in fast, too, sometimes within a day or two of drywall or flooring staying wet, and it can linger long after everything else has been cleaned up.
The mental health toll is easy to overlook but very real. People who live through a major flood often deal with ongoing stress, anxiety, or, in some cases, symptoms consistent with PTSD, particularly if they lost a home or had to be rescued.
Financially, flooding is one of the costliest natural disasters in Canada. Floods and flooding damage houses, vehicles, businesses, and roads. Take the 2024 Toronto flood, a single storm caused $940 million in insured losses.
Flooding also damages electrical infrastructure and triggers utility shutdowns, leaving homes without electricity when it matters most. The EcoFlow DELTA Pro 3 Portable Power Station can help bridge that gap, with capacity up to 48kWh for anywhere from a day to a week of home power, and enough output to run a 3-ton central AC along with other essentials.
How to Prepare for Floods
A little preparation can go a long way here, and most of it doesn't take much time.
Build an emergency kit: At minimum, that means enough water and non-perishable food for a few days, a first aid kit, a flashlight, and any medications your household needs regularly.
Sign up for local weather alerts: Most municipalities and provinces offer free flood warning systems. WeatherCAN, the free app from Environment and Climate Change Canada, sends local watch and warning notifications straight to your phone. Alert Ready goes a step further during a life-threatening flood, pushing warnings automatically to compatible phones through cell towers, no app or sign-up required.
Learn your area's flood risk: Flood maps are usually available through your municipality or province, and they can tell you whether you're in a floodplain or a lower-risk area. From there, put together a basic evacuation plan, so you're not figuring it out in the moment.
Keep a backup power source on hand: The EcoFlow DELTA Pro Portable Power Station was built specifically for home backup, with capacity that expands up to 25 kWh and can power most common household appliances. It can keep a sump pump running, charge phones, and power medical devices, lighting, or even a fridge if utilities go down during a storm. If the outage runs long, it can even be recharged at EV charging stations rather than sitting idle waiting for the power to come back.
What to do During and After a Flood
If flooding is happening now, move to higher ground and stay there. Never walk or drive through floodwater. It doesn't take much moving water to sweep a person off their feet or carry a vehicle off the road, and it's often impossible to tell how deep the water is or what's underneath it.
Follow official alerts and instructions as they come in, even if they seem overly cautious. Conditions do change quickly during a flood, and local authorities usually have more current information than what's visible from your window.
Once it's safe, document damage with photos before cleanup, since claims go more smoothly with clear evidence. Watch for mould, avoid contact with floodwater, and have an electrician check any submerged wiring before the power comes back on. Lean on local recovery resources if it's too much to handle alone.
Staying Ahead of the Next Flood
Flooding is becoming frequent and more severe in a lot of parts of the country, but that doesn't mean there's nothing you can do about it. Knowing your risk, having a plan, and keeping backup power ready before a storm hits are all things that make a real difference when the water starts to rise.
Don't wait until a flood warning is already on your phone to start preparing. Take a few minutes this week to check your flood risk, put together a kit, and make sure you have a way to keep the essentials running if the power goes out. A backup power station from EcoFlow is one straightforward way to cover that last part before the next storm rolls in.
FAQs
Can flooding happen without rain?
Yes. Rainfall isn't the only cause of flooding. Rapid snowmelt, ice jams on rivers, dam or levee failures, and coastal storm surges can all lead to flooding even on a dry, sunny day.
Are some areas more prone to flooding than others?
Yes. Low-lying areas, floodplains, and locations near rivers or coastlines generally face higher flood risk. Urban areas with a lot of pavement can also be vulnerable, since less water is able to soak into the ground.
What should be in a flood emergency kit?
Three days of water and non-perishable food is the baseline. Beyond that, pack whatever prescription medications your household needs, a first aid kit, and important documents in a waterproof bag so they survive even if the basement doesn't.
An EcoFlow power station is worth including too, since it'll keep phones charged and other essentials running if the power stays out longer than planned.