These are short answers to the sewer questions homeowners ask most often, each written to be useful on its own. Longer explanations, with the reasoning and the sources, are on the guide pages linked from each topic. If your question is about safety, the rule is the same throughout: get into fresh air or away from the water first, then work out the cause.
- Smells are usually a lost water seal; backups are usually a blockage or a full main.
- Counting affected drains tells you whether it is a fixture or the main line.
- Insurance covers sewer backup only with optional coverage.
- Check any contractor on the provincial register and keep the camera video.
01 /How should I use these quick answers?
Find your question, read the short answer, and follow the link for the detail when the answer matters to a decision. The questions are grouped loosely: smells first, then backups and clogs, then pipes and cold weather, then money, then hiring. Answers that depend on your city or province say so, and the regional details checked for this site are on the across Canada page.
For a symptom you cannot place, the Sewer Symptom Triage sorts it by what, where and when. For hiring, the vetting checklist turns province rules into questions. Deeper answers are in the guides on smells, backups, insurance and repair options.
FAQAll questions
What does sewer smell actually smell like?
Most people describe rotten eggs, sometimes mixed with an ammonia or musty note. The rotten-egg part is mainly hydrogen sulfide.
Why does my bathroom sink smell like sewer when I run water?
Running water can disturb a trap that is barely holding, pushing drain air out, or the smell is coming from grime in the sink overflow channel. Clean the overflow and check the trap stays full.
Can a sewer smell come from the water heater?
A rotten-egg smell only from hot water taps usually comes from a reaction inside the water heater, not the sewer. A smell near a gas water heater could be gas; leave and call the utility if unsure.
Why does it smell like sewer in the house but nothing is backed up?
Because smells travel through air paths, not water. A dry trap, a toilet seal, a loose cap or a cracked vent lets drain air in while drainage works normally.
What kills sewer smell in a drain?
Refilling the trap with water fixes most drain smells. Deodorisers only mask odour; a smell that returns means a seal or vent needs fixing.
What is the first sign of a sewer backup?
Often gurgling or slow drainage at the basement floor drain or lowest toilet when other fixtures run, before any water appears.
Can a sewer back up into a washing machine?
Water can back up into a standpipe or laundry tub when the main is restricted, because they are low openings. The washer itself is usually protected by its hose loop, but the floor around it is not.
Why does my sewer keep clogging in the same place?
A physical defect is catching debris there: roots at a joint, an offset, a sag or a break. A camera run shows which.
Can my sewer line freeze in winter?
Yes, where a section is shallow, especially under cleared driveways where frost goes deeper, or where a line has a sag that holds water. Slow flow on long cold nights raises the risk.
Should there be standing water in a sewer cleanout?
No. A healthy line drains empty between uses. Standing water in a main cleanout means something downstream is blocking it.
Where does the city's part of the sewer line start?
In many cities at the property line, but it varies. Ask your municipality with your address before paying for work near the line.
Can a tree on the city boulevard damage my sewer line?
Roots do not respect property lines, so a boulevard tree can root into a private lateral. Who pays is set by your municipality's policy; report it and ask.
Is a sewer backup considered flooding by insurers?
No. Insurers treat water rising through drains as sewer backup and water coming over the ground as overland flood. They are separate optional coverages.
Do condo unit owners need their own sewer backup coverage?
Often yes for your unit policy, because the corporation's policy covers the building and common elements, not your belongings or improvements. Check both policies.
Can a sewer backup make my house unsafe to live in?
Sewage on floors, wet porous materials and mould make affected areas unsafe until cleaned and dried. Keep children, pregnant people and anyone with breathing problems out of those areas.
Why is my sewer charge different every month?
In most cities it is calculated from your metered water, so it moves with your water use, the number of days billed and any estimated readings.
What is a sewer contractor?
A company that clears, inspects, repairs or replaces drain and sewer lines. Depending on the province and the work, its workers may need to be certified plumbers.
How do I find a good sewer contractor near me?
Get two or three quotes for the same written scope, check each worker's credential on the provincial register, and collect insurance and clearance documents before signing.
Can I ask a contractor for the camera video?
Yes, and you should. A recorded file with distances is the evidence a repair is based on and is needed for any second opinion.
Is sewer repair without digging always cheaper?
Not always. On a short, shallow line under open lawn, digging can cost less. Trenchless methods win when the surface on top is expensive to restore.
Does a new house ever have sewer problems?
Yes. Construction debris, poorly supported pipe that sags, and missing or unglued joints can show up in the first years. A camera run before the builder's warranty ends is worth considering.
What should I do before buying an older house?
Ask for a recorded camera inspection of the sewer line from inside the house to the main. Older laterals can have clay joints, roots or fibre pipe that a home inspection does not see.
