Sometimes you may walk into a house, and to quote Lynyrd Skynyrd, you think “ooh, that smell.” The house may be clean, but the smell will not go away away. One culprit may be an unused drain.
Every drain should have what we call a p-trap. A p-trap’s main purpose to trap gasses coming up from the sewer and prevent the gasses from entering the house. In order for the trap to block the sewer gasses, the trap must contain water, as the water it was what actually blocks the gas.
However, when a drain goes unused, such as an abandon laundry sink or broken shower, the water in the trap will evaporate over time. When the water level in the trap gets low, sewer gasses can flow in the house.
Not only can sewer gasses make a house smell, they can potentially be dangerous. Sewer gasses may contain methane, carbon monoxide, sulfides, or other potentially toxic gasses, depending on what is in your local sewer.
To fix a dry p-trap, simply pour a glass of water down the drain. If you have no plans to use the drain again, consider having a qualified plumber cap the drain pipe.
A leaking drain pipe actually poses two problems. Not only is there the issue of water damage from the leak, but the potential for p-trap to drain. Which is why on a home inspection an inspector should run water in the drain and inspect the p-trap for leaks.
