Posted on
July 31, 2025
by
Chris Marshall
Basement flooding is a major concern for Calgary homeowners—especially during spring melts and summer rainstorms. A flooded basement doesn’t just mean soggy carpets and damaged furniture; it can lead to mold, structural issues, and thousands of dollars in repairs (with or without insurance coverage).
Here’s what you need to know to prevent flooding, and the emergency steps to take if it ever happens to you.
🔧 How to Prevent Basement Flooding in Calgary
When water tables rise without a system to clear the water this puts massive pressure on foundations, causing water seepage through 1) the seam between the basement wall & the basement floor 2) cracks in the floor 3) cracks in the wall
1. Keep Your Gutters and Downspouts Clear
Clogged gutters and short downspouts are one of the biggest culprits. When water can’t drain far away from your home, it can pool near the foundation and seep into your basement.
✅ Clean gutters in spring and fall
✅ Extend downspouts at least 6 feet from the foundation
✅ Consider installing downspout extenders or splash blocks
2. Grade Your Yard Away from the House
If your landscaping slopes toward your home, water will follow. Make sure soil slopes away from the foundation to direct water away naturally.
✅ Add soil around your foundation to improve grading
✅ Avoid planting large shrubs right next to your home—they can trap moisture
If you neighbour’s yard drains into your yard, make sure that you account for draining this extra water.
3. Install (Maintain) a Sump Pump
A sump pump is your basement's best friend. It collects water from around your foundation and pumps it safely away. Make sure yours is:
Functioning properly & draining far enough away from your foundation (and not into your neighbour’s foundation)
Connected to a power source (with a battery backup in case of outage)
Checked annually or after a major rainfall
Tip: Consider installing a high water alarm to alert you before flooding occurs. Once installed let your insurance company know - you could be eligible for a discount. (available at your local hardware store or amazon).
If you have a sump pump in your basement, here’s what you should keep in mind to prevent flooding—especially during Calgary’s wet spring and summer seasons:
If your sump pump runs often—like daily or even more—your home could be at higher risk if the pump ever fails. It’s a good idea to install a backup pump that kicks in if the main one stops working.
Make sure your sump pump has backup power. In a storm, power outages are common—and that’s when you need your pump the most. Use a battery backup or generator, not one that runs on drinking water.
Check for a one-way (check) valve on the discharge pipe. This keeps the water that’s already been pumped out from flowing back into the pit.
Ensure the discharged water flows well away from your home’s foundation. If the water ends up back near the house, the pump will just keep recycling the same water.
Add a sump pit water alarm. These devices let you know when the water level is rising too high. Some even send alerts straight to your phone—especially helpful if you're away from home. Look for alarms that also warn you if the pump doesn’t turn on when it should.
Use a sealed sump lid. This helps keep harmful radon gas from leaking into your home through the sump pit.
Test your pump regularly. Just pour water into the pit to make sure the pump turns on and drains properly. It’s an easy way to catch problems early.
Replace the sump pump every 10 years—or sooner if it shows signs of wear, runs constantly, or struggles to keep up.
4. Inspect and Maintain Foundation Cracks
Even small foundation cracks can allow water to seep in over time. Calgary’s freeze-thaw cycles make this even more likely.
✅ Seal small cracks with waterproof concrete sealant
✅ Have larger or shifting cracks inspected by a professional
5. Check Your Window Wells
Basement windows are vulnerable, especially if the wells fill with water.
✅ Ensure window wells are clear of debris
✅ Install window well covers to prevent rain or snow buildup
✅ Make sure there is proper drainage at the bottom of each well
6. Limit Water Usage During Heavy Rain
When Calgary's storm-water system is overwhelmed, your sewer line may back up—especially during heavy rain.
✅ Avoid running dishwashers, washing machines, or long showers during big storms
✅ Install a backwater valve to prevent sewage from backing up into your basement
💧 What to Do If Your Basement Floods
Even with the best prevention, flooding can still happen. Here’s what to do:
Step 1: Stay Safe
If water is near electrical outlets or appliances, do not enter the basement until power is shut off.
Wear boots, gloves, and a mask—floodwater can be contaminated.
Take photos & videos as much as possible.
Step 2: Stop the Source
If it’s from a broken pipe or sump pump failure, shut off the water or power.
If it’s due to rain, wait for the weather to pass and the water to stop rising.
Step 3: Call a Professional
Contact a water damage restoration company as soon as possible.
If it’s safe to do so, document the damage for insurance: take photos and videos.
Step 4: Start Water Removal
Use a wet/dry shop vac, pump, or mop to remove standing water
Remove wet carpets, drywall, and belongings quickly to prevent mold
Step 5: Dry and Dehumidify
Step 6: Call Your Insurance Provider
🧰 Final Tips for Calgary Homeowners
Install a backwater valve.
Inspect your sump pump every spring.
Review your home insurance policy to ensure it includes sewer backup and overland flood coverage.
In Summary
Basement flooding is an unfortunate risk in Calgary, but it’s one that can be largely managed with the right preparation. From grading your yard and maintaining your sump pump to knowing what to do if flooding does happen, a proactive approach can save you major costs and headaches.
If you're unsure about your home's risk, consult a licensed plumber or waterproofing specialist who understands Calgary's soil and seasonal risks.
