Sewer smell throughout the house

Symptoms

• Smell noticeable in more than one room
• Odor seems to come and go
• Smell is worse in a basement or lower level
• No single drain seems to be the clear source

Likely causes

• CommonDry floor drain trap in a basement or garageFloor drains are used infrequently and their traps evaporate dry easily.
• PossibleBlocked or damaged roof vent stackA blocked vent can let sewer gas find alternate paths into the home.
• PossibleMain sewer line partial blockage or damageCan allow gas to escape into the home through various points.
• PossibleDried-out trap under a rarely used sink or laundry standpipeSimilar cause to a single-fixture smell but affecting a broader area.

What to do

1. Check any floor drains in the basement or garage and pour a bucket of water into each to refill their traps.
2. Check all rarely used sinks, tubs, and the laundry standpipe and run water in each briefly to refill their traps too.
3. Wait a day and see if the smell returns despite refilled traps, which points to a bigger issue.
4. Look outside for the roof vent stack and check for obvious blockage if it's safely visible without climbing on the roof.
5. Note whether the smell correlates with rain, since a main line issue can sometimes worsen with heavy rain infiltration.
6. If the smell persists across multiple fixtures and doesn't resolve with refilled traps, treat it as a sign of a bigger sewer venting or line issue.

Tools and parts

• Bucket

When to call a pro

Call a plumber if refilling all traps doesn't resolve the smell, since it likely points to a vent stack or main sewer line issue that needs inspection.

Safety