If you’ve noticed a sewer smell in your house during winter, you’re not alone. Many homeowners across Durham Region experience this problem once colder weather sets in. The smell can appear suddenly, linger for days, or come and go without warning.
What makes winter especially frustrating is that sewer odours often show up even when drains seem to be working fine. In most cases, the smell isn’t caused by a single issue. In this article, the experts at Caldwell Plumbing will explain how winter conditions can make these issues harder to ignore.
Why Sewer Smells Are More Noticeable in Winter
Winter changes how your home “breathes.” Once the heat is on, windows stay closed, doors stay sealed, and fresh air circulation drops. Any odour inside your home has fewer places to escape.
At the same time, plumbing systems rely on airflow to safely vent sewer gases out of the house. When airflow is reduced, those gases are more likely to linger indoors instead of being carried outside where they belong. What may have been a faint smell in warmer months can suddenly feel overwhelming in winter.
How Cold Weather Affects Your Drain and Sewer System
As the ground cools, soil shifts and moisture levels change. Drain flow can slow slightly, and pressure inside sewer lines behaves differently.
Inside the home, temperature differences between warm indoor air and cold outdoor air can disrupt how plumbing vents draw air upward.
These small changes don’t always cause drain blockages or water leaks, but they can allow sewer gases to move in directions they normally wouldn’t.
Common Causes of Sewer Smell in the House During Winter
Sewer odours almost always have a specific source. Winter just makes those sources easier to notice.
1. Dry or Evaporated Drain Traps
Every drain in your home has a trap that holds a small amount of water. That water creates a seal that blocks sewer gas from coming back up the pipe. In winter, floor drains, basement sinks, or guest bathrooms that aren’t used often can dry out.
When the trap dries, sewer gas has a direct path into your home. This is one of the most common causes of a sewer smell in the house in winter.
2. Blocked or Poorly Venting Plumbing Stacks
Your plumbing system relies on vent pipes that extend through the roof. These vents allow sewer gases to escape safely outside. In winter, vents can become partially blocked by snow, frost, or debris.
When that happens, pressure builds in the system, and gases may be pushed back through drains instead of venting upward. The result is an unpleasant sewer smell that seems to come from nowhere.
3. Partial Sewer Line Blockages
A sewer line doesn’t have to be fully blocked to cause odours. Grease buildup, debris, or tree roots can restrict flow just enough to trap gases.
In winter, slower movement through the line can make smells more noticeable, even before any backup occurs.
Why Sewer Smells Often Come and Go
One of the most confusing things for homeowners is how inconsistent sewer smells can be. You might notice it in the morning, after doing laundry, or only on very cold days. That’s because sewer gas movement is affected by water use, temperature changes, and air pressure.
Running water can temporarily refill a dry trap. A warm afternoon can improve venting. These short-term changes may mask the smell, but they don’t fix the underlying issue. If the smell keeps returning, it’s a sign that something still needs attention.
What Homeowners Can Check Safely Before Calling a Plumber
You don’t need to take anything apart to gather useful information. Paying attention to a few details can help identify the problem faster.
Take note of:
- Which rooms or drains smell the strongest
- Whether the smell appears after using water
- If more than one fixture is affected
Avoid pouring chemicals down drains or sealing vents yourself. These fixes often make the situation worse and can create safety risks.
When to Call a Plumber for Sewer Smells
It’s time to call a licensed plumber if:
- The smell lasts more than a few days
- Multiple drains are affected
- You notice gurgling sounds or slow drainage
- Odours return repeatedly despite basic checks
Caldwell Plumbing helps homeowners across Durham Region identify the real cause of sewer smells, not just mask the symptoms. Depending on the situation, this may include camera inspections or professional drain cleaning.
Our licensed and insured plumbers use proven methods to locate the source of odours quickly and efficiently resolve the issue.
Don’t Ignore Sewer Smells This Winter
A sewer smell in winter is a sign your plumbing system needs attention. Addressing the issue early protects your home, your comfort, and your indoor air quality.
Contact us today to schedule an inspection or request service. We’re here to help eliminate winter sewer odours and keep your home running smoothly across Durham Region.
FAQs
Will pouring water down drains permanently fix sewer smells?
It may help temporarily if the issue is a dry trap, but recurring smells usually point to a deeper problem that needs professional attention.
Is a sewer smell in winter dangerous for my health?
Occasional odours are usually not harmful, but ongoing sewer smells can affect indoor air quality and should be inspected by a professional.
Can sewer smells come from a neighbour’s plumbing or shared sewer line?
In some cases, yes. Homes connected to shared or municipal sewer lines can be affected by nearby blockages or pressure changes.
Why does the sewer smell seem stronger in the basement?
Basements often have floor drains or unused fixtures where drain traps can dry out, allowing sewer gas to enter more easily.
