Calgary sewer trouble, solved in the right order.
Backups, clogs, roots and freeze-ups, sorted by symptom: what to do first, when to call 311, when to call a contractor, and how to keep it from happening again in a Calgary year of cold snaps, chinooks and summer storms.
CalgarySewers.com is an independent help desk for Calgary homeowners with sewer and drain problems. It turns a symptom, such as a floor drain backing up, a line that keeps clogging, roots or a freeze-up, into the right next step in the right order: make it safe, decide whether it is the City's side or yours, call 311 or a vetted contractor, then prevent it.
Play twelve months of Calgary weather through one house's sewer line
Scrub the month or play the whole year, and switch the house features the Season Calendar asks about: a backwater valve, a sump, a big tree and the era the home was built. Every job the model lists is tagged as yours or as a 311 call.
What the model shows, in words
Winter attacks the shallow parts first
From November to February the hatched frost band thickens, and it drives furthest under the cleared driveway and road, where no snow insulates the ground. The first thing it reaches in the model is the exterior cleanout riser and the shallow run near it, not the deep main. A frozen private line is the owner's to have thawed, usually from the cleanout; the frozen sewer line guide walks through what to stop doing and who to call.
A chinook moves months of melt into one afternoon
February shows the chinook arch in the sky and the snowpack collapsing. Meltwater that cannot sink into frozen soil heads for the foundation, and water ponds in the street where the storm inlet is iced over. That pond is a 311 report if it lingers, while the floor drain check afterwards is a household job. Chinooks and your drains explains why the refreeze that follows can be worse than the thaw.
Summer storms push the main back toward the house
In June and July the main in the street fills and the flow backs up the service line. With the backwater valve switched on, its flap drops shut at the valve and the basement stays dry, provided nobody runs water indoors. Switch the valve off and the same storm comes up through the floor drain instead. Several homes affected in one downpour is the pattern that points to the City's pipe, as storm surcharge or private blockage sets out.
Groundwater and roots follow their own calendars
The dashed blue line is groundwater, rising through April and May as the melt soaks in. Without a sump it seeps along the wall base, which is a seepage problem rather than sewage. Turn on the big tree and a jointed older line collects roots from May to September, while a PVC-era line shows gasketed joints holding them out. The model never cuts them for you: that belongs in a root-cutting window described in tree roots in a Calgary sewer line.
Every job carries a name
The panel lists what the month asks of the house, and each line wears an owner tag or a 311 tag. The tags follow the City's published split, with the City responsible from the main to the property line and the owner from there to the house, and the same rules the City or Owner triage uses. For a month-by-month list built for your own house, open the Calgary Sewer Season Calendar. All levels in the model are illustrative.
What is happening with your sewer?
Pick the closest match. Each path goes to the guide that answers it in full.
City or Owner? Responsibility Triage
City or Owner? asks where the problem shows, whether neighbours are affected, whether it is during heavy rain, and what a camera found. It then applies five rules to suggest a first call: 311 because the City is likely involved, 311 for a possible main surcharge, a shared case for 311 with footage, a likely owner case for a drain contractor, or start with the owner side.
How the City or Owner? Responsibility Triage works →
Also freeCalgary Sewer Season Calendar
A 12-month Calgary sewer maintenance calendar, personalized by home era, backwater valve, sump pump and trees, with the current month highlighted.
City or Owner? Responsibility Triage
Read these first
Sewer backup in Calgary, in order
Protect people, stop water use, call 311, clear the cleanout, call the insurer, then hire for the private side.
CornerstoneCity or Owner? triage
Four questions about symptoms, neighbours, rain and camera results, five rules, and the City's published ownership split every time.
CornerstoneCalgary Sewer Season Calendar
A 12-month maintenance rhythm for cold snaps, chinooks, melt, storms and freeze-up, personalized to your house.
CornerstoneVetting a Calgary contractor
Business licence, journeyperson plumber, permits, WCB-Alberta clearance, insurance and red flags.
What it looks like down there
Illustrations of what this work involves and what a camera or a trained eye picks up. Every guide on CalgarySewers.com carries more like these.
01 /What does the Calgary sewer help desk do?
It answers the question every Calgary homeowner has when a drain misbehaves: what do I do now, and who do I call? Most sewer trouble in a house comes down to a handful of situations, a backup, a stubborn clog, roots, a freeze-up, water in the basement after a chinook or a storm, and each one has a sensible order of steps. Doing them in the wrong order costs time and money: paying a contractor to chase a surcharged City main, waiting on the City for a blockage in your own front yard, or pouring chemicals into a line that someone later has to open.
Every guide here starts from a symptom and ends with a next step. Where the City of Calgary or the Government of Alberta publishes a rule or a process, the guides say so and point to it; where something depends on your address, they tell you to confirm it through 311. HAUSE Sewer is an independent information and service-request network. It does not do plumbing, drain or sewer work, and it is not a contractor.
If sewage is coming up right now: get people away from the water, stop all water use in the building, and keep clear of anything electrical the water touches. Then follow what to do in a Calgary sewer backup.
02 /Who handles what: the City of Calgary or you?
The City of Calgary publishes the split plainly in the description of its sanitary service line data. The sanitary service pipe has two sections: from the sanitary main to the property line, owned and maintained by The City of Calgary; and from the property line to your house, owned and maintained by the homeowner.
In practice, 311 is the front door for anything that might involve the City: a backup that rises with your water off, several neighbours affected in a storm, sewage at a manhole, a sinkhole in the boulevard, or a camera finding at or past your property line. A City crew may snake from your cleanout toward the main to find which side a blockage is on. Private-side blockages, repairs and basement cleanup are the owner's. The City makes the final determination in any specific case. The City or Owner triage tool sorts the common situations in a minute, and what the City does for sewer problems explains the rest. Once the call is made, after you call 311 covers status updates and the crew's report, and what a sewer backup costs splits the bill into its layers.
03 /What should you do first? Start with the symptom
| What you see | First move | Read next |
|---|---|---|
| Water or sewage coming up the basement floor drain | Stop all water use; call 311 for triage | Sewer backup in Calgary |
| Backup during a storm, neighbours affected too | Call 311; check your backwater valve | Storm surcharge or private blockage |
| Floor drain gurgles when the toilet flushes | Run the two-fixture test; book a main-line clearing | Main line clog |
| One sink or tub slow | Clean the strainer; plunger or hair tool | Best drain unclogger |
| Roots found on camera | Cut, camera, locate, then plan the fix | Tree roots in Calgary |
| Drains stopped in a deep cold snap | Stop water use; hot-water thaw from the cleanout | Frozen sewer line |
| Water along the basement wall after a chinook | Treat as seepage; check downspouts and sump | Sewage, seepage or leak? |
| Sewage in the street or at a manhole | Call 311 | After-hours emergencies |
| Basement shower or toilet fills when other drains run | Stop water use; clear the main, not the fixture | Basement toilet and shower backups |
| Backup in a condo or townhouse | Call the manager or board first; 311 for the main | Condo and townhouse backups |
When the symptom is unclear, the question that matters most is simple: does the water rise only when someone uses water, or with everything off? The first points to your own line; the second points away from it.
04 /Why do Calgary sewers behave the way they do?
Two things shape almost every Calgary sewer problem: the weather and the era of the house. The weather gives Calgary its own sewer calendar. Deep cold snaps freeze shallow lines and frost roof vents; chinooks melt a snowpack in hours and send the water to foundations and iced storm drains; spring melt raises groundwater; summer storms and hail surcharge mains and plug gutters; fall is the short window for cleaning and repairs before frost; and the holidays bring grease. The Calgary sewer seasons page walks through each, and the season calendar turns them into a month-by-month plan for your house.
The era of the house predicts the pipe. The City publishes the material and installed year of the City-owned portion of each residential sanitary service line. In HAUSE's 2026 analysis of that data, about one in five City-side lines citywide are coded TIL, 3.3 percent are cast iron and about two-thirds are PVC; in communities the City classifies as 1960s/1970s, the TIL share is 77.5 percent. The data covers only the City's portion from the main to the property line, so your private portion can be a different material and age. For community-by-community figures and an address lookup, see CalgarySewers.ca, the network's data site.
05 /How do you find and vet local help in Calgary?
Check the business before you let it into the basement. The City of Calgary requires a business licence for contractor businesses, including plumbers, and offers a Licensed Trade Contractor search. Plumber is a compulsory certification trade in Alberta, so repairs and replacements must be done by certified journeypersons or supervised apprentices, under a City permit where one is required; clearing a blockage does not need a permit. Ask for a WCB-Alberta clearance letter and a certificate of liability insurance, and if a business wants money before the work is finished, check its Alberta prepaid contracting licence.
Then insist on evidence: a camera run to the main, the video, the footage-counter distance to any defect, and whether it is before or past your property line. That footage is what makes a 311 call, an insurance claim and a repair decision straightforward. The full checklist is in how to vet a Calgary drain contractor, the planning ranges for common calls are on the service call cost page, and a quote request puts your details in front of local contractors.
Every guide on CalgarySewers.com
After-hours sewer emergency in Calgary: what cannot wait until morning
Night or weekend sewer problem in Calgary? What counts as an emergency, when to call 911, 311 or a contractor, and how to hold the house safely until morning.
Backwater valve maintenance in Calgary: checks, service visits and common faults
Backwater valve maintenance for Calgary homes: which valves need yearly service, a safe owner check, what a service visit includes, faults and suite rules.
Water in a Calgary basement: sewage backup, seepage or a leak?
Water in your Calgary basement? Tell a sewer backup from groundwater seepage, overland flow, a sump failure or a supply leak, and learn who handles each one.
Condo and townhouse sewer backups in Calgary: who handles what
Sewer backup in a Calgary condo or townhouse: who to call first, shared stacks and laterals, Alberta's 2026 chargeback rules, and what records to keep.
Sewer backup in Calgary: what to do, in the right order
Sewer backup in Calgary? The order that works: protect people, stop water use, call 311 for triage, clear the cleanout, call your insurer, then a contractor.
Storm surcharge or private blockage? How to read a Calgary backup
Calgary sewer backup: a surcharged City main or a blockage in your own line? Use rain, neighbours and a water-off test to tell, then call the right party.
After you call 311 about a sewer backup: updates, the crew visit and what comes next
After calling 311 about a Calgary sewer backup: how to get status updates, what the crew asks of you, the Customer Service Report, and next steps by outcome.
What the City of Calgary does for sewer problems, and what it leaves to you
City of Calgary sewer services for homeowners: backup triage, City-side lines, storm drains, public trees, lateral lining and what the City won't do.
Where does Calgary's sewage go, and why it matters for your drains
Where does Calgary sewage go? Through your service line and City mains to Bonnybrook, Fish Creek or Pine Creek, then the Bow River, and why it matters.
Basement toilet or shower backing up in a Calgary house: what it means and what to do
Basement toilet or shower backing up in Calgary? Read the symptom, check for a sewage pump, know what you can safely try, and when to call 311 or a contractor.
What is the best drain unclogger? The right order of tools
Best drain unclogger or drain cleaner? The order of tools that works, why chemicals come last, and how to clean a drain catcher or draining board drain.
Drain cleaning in Calgary: matching the service to the clog
Drain cleaning in Calgary: which service fits your clog, cable or jetting, why the camera matters in older communities, and how to judge a company.
Main line clog in a Calgary house: find it, clear it, stop it coming back
Main sewer line clog in a Calgary home? Where clogs form in bungalows, split-levels and newer builds, what to ask when you book, and how to stop repeat clogs.
What a sewer backup costs in Calgary, layer by layer
How much a sewer backup costs in Calgary in 2026: clearing the line, camera, City-side cases, cleanup, repairs and prevention, with planning ranges.
Commercial and multi-unit drain cleaning in Calgary: who calls whom
Commercial drain cleaning in Calgary: who is responsible under leases and condo bylaws, grease and wipes in shared lines, scheduling, and vetting contractors.
How to vet a Calgary drain or sewer contractor
Vetting a Calgary drain or sewer contractor: City business licence, journeyperson plumber, permits, WCB clearance, insurance, prepaid licence, red flags.
Tree roots in a Calgary sewer line: what to do, and when
Roots in your Calgary sewer line? Which trees are involved, what you may do about City trees, when to cut, and when cutting stops making sense.
Chinooks and your drains: Calgary's freeze–thaw problems, and fixes
How Calgary chinooks affect drains: iced storm drains, meltwater at the foundation, frozen downspouts and sump lines, roof vent frost and cleanout damage.
Frozen sewer line in Calgary: signs, safe thawing and prevention
Frozen sewer line in a Calgary cold snap? Which lines freeze, how to tell ice from a clog, how pros thaw it, what not to do, and how to prevent it.
Spring melt to hail season: a Calgary basement backup plan
Calgary spring melt, storms and hail: keep sewage and water out of the basement, from backwater valve tests and gutter cleaning to a storm-day routine.
What a drain or sewer service call costs in Calgary (2026 planning ranges)
Calgary drain cleaning prices, 2026 planning ranges: main line clearing, branch drains, camera, jetting, root cutting, frozen lines and after-hours calls.
Calgary Sewer Season Calendar
A 12-month Calgary sewer maintenance calendar, personalized by home era, backwater valve, sump pump and trees, with the current month highlighted.
City or Owner? Responsibility Triage
Is your Calgary sewer problem the City's or yours? Answer four questions about symptoms, neighbours, rain and camera results to see who to call first.
Calgary's sewer seasons, and what each one asks of your house
Calgary's sewer year, season by season: cold snaps, chinooks, snowmelt, storm and hail season, freeze-up and holidays, and how home era changes the risks.
Frequently asked
What should I do if my Calgary basement floor drain is backing up?
Keep people away from the water, stop all water use in the building, avoid anything electrical, and call 311. The 311 agent decides whether you need a plumber or whether City infrastructure may be involved; a City crew may snake from your cleanout to find which side the blockage is on.
In Calgary, which part of the sewer line is mine?
The City's published split: from the sanitary main to the property line, the City owns and maintains the pipe; from the property line to the house, the homeowner does. The City makes the final determination for specific cases.
Does the City of Calgary clean drains?
Not private drains. The City triages backups through 311 and investigates which side a blockage is on. Clearing and repairing the private side is the owner's job, usually with a drain contractor.
When should I call 311 instead of a plumber?
Call 311 when water rises with all your water off, neighbours are affected during heavy rain, sewage appears in the street or at a manhole, the boulevard has a sinkhole or wet spot, or a camera shows a defect at or past your property line.
Is CalgarySewers.com a plumbing company?
No. HAUSE Sewer is an independent information and service-request network. It does not perform work. It explains the steps and can connect you with local contractors when you request quotes.
What is the best time of year for sewer maintenance in Calgary?
Test the backwater valve and sump in spring before storm season, cut roots in late spring and summer, and book main-line cleaning and repairs in September or October before freeze-up.
How much does it cost to clear a main sewer line in Calgary?
As a 2026 planning estimate before GST, a main-line clearing from an accessible cleanout in business hours typically quotes about $200 to $450. Access, roots, length and time of day move it; it is an estimate, not a quote.
Describe the problem once. Get a straight answer.
Send the symptoms and anything you already know — age of the house, what a camera found, what you have been quoted. The HAUSE Sewer desk replies with next steps and, where available, a local contractor for the job.
Sewage backing up right now? Stop using water, keep people away from the water, and do not touch electrical equipment near it.