Sewer Backup in Calgary: Who to Call and What to Do First

A sewer backup is one of the most unpleasant plumbing emergencies a Calgary homeowner can face. The smell alone is enough to make most people feel sick, and the health risks are real — raw sewage contains bacteria, viruses, and other pathogens that can cause serious illness. Knowing what to do in the first few minutes can make a significant difference to both your health and the extent of the damage.

This guide covers exactly what to do when you discover a sewer backup, how to figure out whether it's your problem or the City's, and what you can do to prevent it from happening again.

Recognizing a Sewer Backup

Sewer backups don't always announce themselves dramatically. Many Calgary homeowners first notice a sewer backup as:

• Gurgling sounds coming from floor drains, toilets, or tub drains — especially in the basement.
• Slow drains throughout the house (not just one fixture).
• Water or sewage backing up through floor drains when you run water elsewhere in the house.
• A strong sewage smell coming from drains, particularly in the basement.
• Sewage visible in the basement floor drain or backing up through a toilet.

If multiple drains in your home are slow or backing up at the same time, that's a strong indicator of a main sewer line blockage rather than a single clogged drain. This needs professional attention immediately.

Immediate Steps: What To Do Right Now

1. Stop using all water fixtures immediately. Every time you flush a toilet, run a tap, or use the washing machine, you're adding more water to an already blocked system. This makes the backup worse.
2. Keep everyone away from the affected area. Raw sewage contains pathogens that can cause illness. Don't let children or pets into the basement or any area where sewage has backed up.
3. Open windows for ventilation if there's a strong sewage smell. This helps reduce the concentration of harmful gases.
4. Don't try to clean up the sewage yourself until the blockage has been cleared and the source of the problem has been addressed. Cleaning up before the blockage is fixed is pointless — it will just back up again.
5. Call an emergency plumber in Calgary immediately. A sewer backup is not a situation to wait on. Call our emergency plumber Calgary line at (403) 771-5925.

Is It Your Problem or the City's?

This is one of the most common questions we hear during sewer backup calls. The answer depends on where the blockage is located.

Your private sewer lateral — the pipe that runs from your home to the municipal sewer main in the street — is your responsibility to maintain and repair. Any blockage within your property is yours to deal with.

The municipal sewer main in the street is the City of Calgary's responsibility. If the blockage is in the main, the City needs to clear it.

How to Tell the Difference

A blockage in your private lateral typically affects only your home. A blockage in the municipal main may affect multiple homes on your street. If your neighbours are also experiencing sewer backups at the same time, that's a strong indicator of a municipal main issue.

When we arrive for a sewer backup call, one of the first things we do is determine whether the blockage is in your private system or the municipal system. If it's the City's problem, we'll advise you to contact the City of Calgary wastewater services directly. We can help you understand the process and what to expect.

What Causes Sewer Backups in Calgary?

Understanding the cause of your backup helps prevent it from happening again. Common causes include:

• Grease buildup: Cooking grease poured down the drain solidifies inside pipes over time, gradually restricting flow until a blockage occurs.
• Tree root intrusion: Roots from trees and shrubs grow into sewer lines through small cracks. Over years, they can completely block the pipe.
• "Flushable" wipes: Despite the label, these products don't break down in sewer lines and are a major cause of blockages.
• Collapsed or damaged pipes: Older clay or cast iron pipes can crack, collapse, or shift, restricting or blocking flow.
• Heavy rain events: During significant rainfall, the municipal sewer system can become overwhelmed, causing backflow into private drain systems.

Preventing Future Sewer Backups

Once we've cleared your current backup, here are the steps that will most effectively reduce your risk of a repeat:

• Never pour grease down the drain. Let it cool and solidify, then dispose of it in the garbage.
• Only flush toilet paper. Nothing else — not wipes, paper towels, cotton balls, or hygiene products.
• Have your drain lines professionally cleaned every 2–3 years, especially in older homes or if you have mature trees near your sewer line.
• Consider a backwater valve. This device prevents municipal sewer backflow into your home during heavy rain events. The City of Calgary has historically offered rebate programs for backwater valve installation — check the City of Calgary website for current programs.
• Have your sewer line inspected with a camera if you're in an older home or have had repeated backups. This can identify root intrusion, cracks, or other issues before they cause a major problem.

After the Backup: Cleanup and Insurance

Once the blockage has been cleared, you'll need to clean and disinfect the affected area. Sewage cleanup is not a DIY job — it requires proper protective equipment and disinfection products. Many home insurance policies cover sewer backup damage, so contact your insurer as soon as possible. Document all damage with photos before any cleanup begins.

For more guidance on handling the immediate aftermath of any plumbing emergency, see our guide: What To Do Before Your Emergency Plumber Arrives in Calgary.

Call Our Sewer Backup Team in Calgary

If you're dealing with a sewer backup right now, call our 24 hour plumber Calgary line at (403) 771-5925. We respond 24/7 and will clear the blockage and advise you on next steps. You can also learn more about our sewer backup and drain cleaning service.