Why Is There a Sewer Smell Coming from My Drains, Yard, or Basement?

If you notice a sewer smell in your home or yard, it’s a sign that something is wrong with your septic system. That smell isn’t just unpleasant - it could mean wastewater isn’t draining properly or that harmful gases are escaping where they shouldn’t be.

If you live in Edmonton, Lac Ste. Anne County, Parkland County, Sturgeon County, or Strathcona County, you know that Alberta’s cold weather and unique soil conditions can make septic problems worse. Let’s go over the common reasons your septic system might be giving off a bad smell and what you can do about it.

1. Your Septic Tank Is Too Full

A septic tank holds wastewater and solids until they break down naturally. Over time, solid waste builds up, and if the tank isn’t pumped out, it can overflow or clog the system. When this happens, gases that should stay trapped inside the tank can escape through drains, toilets, or even the ground above your septic field.

🔹 Solution: If it’s been more than 2-3 years since your last pumping, it’s time to schedule one. A full tank can lead to serious damage if left unchecked.

2. Your Septic Vent Is Blocked

Septic systems have vent pipes that release gas safely outside. These vents usually run up through your roof. If they get blocked by snow, leaves, or debris, the gas has nowhere to go and may come up through your drains instead.

🔹 Solution: Check your roof vent for blockages, especially in the winter. If ice or debris is covering it, carefully clear the area so the gas can escape properly.

3. Your Drain Field Is Failing

Your drain field is the part of the system where wastewater soaks into the ground. If the field is clogged, flooded, or too saturated, sewage can back up and create odors. Signs of a failing drain field include standing water, mushy ground, or extra-green grass in the area.

🔹 Solution: If your drain field isn’t working properly, you need a professional inspection. A failing field can cause major septic issues and may need repair or replacement.

4. A Pipe or Seal Is Leaking

Septic tanks and pipes are designed to be airtight. If a seal cracks or a pipe leaks, bad smells can escape. This is more common in older septic systems or if the ground shifts due to frost, heavy rain, or soil movement.

🔹 Solution: If you notice strong sewer odors outside near your septic tank or field, call a septic professional. Leaks can be hard to find, but they must be fixed or they will only get worse.

5. A Drain Trap Has Dried Out

Every sink, tub, and floor drain has a U-shaped pipe (P-trap) that holds water. This water blocks sewer gases from coming up into your home. If a drain hasn’t been used in a while, the water in the trap can evaporate, letting the smell through.

🔹 Solution: Run water down all your drains regularly to keep the traps full. If the smell is coming from a little-used drain, pour water down it to refill the trap.