A house usually smells like sewer gas because something is letting air from the drain system into the home. The most common causes are a dry drain trap, a failed toilet seal, a blocked or damaged vent pipe, or a crack in a drain or sewer line.
Dry Drain Traps
Every sink, tub, shower, and floor drain has a trap that holds water and blocks sewer gas. If a drain is rarely used, that water can evaporate. Guest bathrooms, basement floor drains, and laundry sinks are common culprits. Running water for a minute in each drain often solves the problem.
Toilet Seals
A wax ring seals the base of each toilet to the drain. If the seal breaks, sewer gas can escape around the base. Signs include a smell near the toilet, a toilet that rocks, or water around the base after flushing.
Vents and Cracked Pipes
Plumbing vents carry sewer gas up and out through the roof. A cracked or disconnected vent inside a wall can release gas into the house. A blocked vent can also pull water out of traps, which lets gas in. Checking roof vents is a job for a professional.
A crack in a drain line inside a wall, under the floor, or in the main sewer line can leak gas. Older cast iron pipes are especially prone to cracking. The smell may be strongest in the basement or near one wall.
Health and Safety
- Sewer gas can cause headaches, nausea, and irritation
- Open windows to air out the home
- If the smell is like rotten eggs and you suspect natural gas instead, leave the house and call the gas company or 911
If refilling traps does not clear the smell, checking the drain and sewer lines can find the source. For odors that come and go, you can have a plumber trace the smell by calling (833) 603-1840.