Why is there a sewer smell in my basement?
A strong sewer smell coming from your basement is most often caused from a dried out floor drain, a bad ejector pit seal, improperly vented appliances or fixtures, or even a damaged sewer line.
Floor Drains – Rarely-used floor drains in your basement are typically the source of the sewer stench. These drains are designed with a trap to hold a small amount of water in order to seal the pipe so sewer gases don’t escape into the home. Over time, that seal can open as the drain dries up (condensation, etc.) from little use, releasing sewer gas into the basement and stinking the place up.
Solution: Dump around a gallon of clean water down the drain to reseal the pipe and keep the odor out of your basement (add a mild household cleaner to the water for a fresh scent).
Note: This applies to rarely-used toilets, as well. If the water in a toilet bowl has dried up, simply flush the toilet again.
Most floor drains also include a cleanout plug inside that sometimes doesn’t get replaced. Without this plug, sewer gas has a direct path into your basement.
Solution: Remove the grate on the drain opening and see if the plug is missing. New plugs can be purchased at about any hardware store.
Ejector Pit & Pump – If your home has an overhead sewer line in the basement, the ejector pit is required to be sealed with a cover and properly vented to contain the waste water. A missing lid, bad seal, or broken/clogged vent will quickly overwhelm your basement with sewer gas.
Solution: Make sure your ejector pit (if you have one) has a properly fitted lid with a good seal. Inspect the waste discharge pipe and vent pipe for any cracks or obstructions. Replace any components as needed to contain the sewer smell.
Vents – Sometimes basement fixtures and appliances don’t get properly vented, preventing sewer gases from exiting the home.
Solution: Confirm that laundry rooms and bathrooms are vented correctly and actually tied in with the rest of the home. This applies to the whole home – sometimes smells originating on a main or upper level can make it to the basement.
Sewer Line – The sewage smell you’re experiencing could be a result of the sewer line being damaged. If this is the case and the leak is close enough to your home, the waste water would leak into the ground and make its way to the sump pit in your basement.
Solution: This is best handled by professionals. The most common troubleshooting method involves a leak tracing dye and running it through the bathtub or toilet and cycling the dyed water through to see if it reaches the soil. If a leak is identified, zeroing-in on the problem area is the next task and will determine how much work will be required to fix the leak (cross your fingers for trenchless pipe repair).
If you still notice the smell after checking these common culprits, contact your preferred plumber for a more thorough inspection.