Under normal circumstances, sewer gas vents outside the home and dissipates into the atmosphere. Plumbing problems sometimes allow the gas to escape in the home, creating an offensive odor. Stopping the odor sometimes requires a few minutes and a pitcher of water. At other times, you might need to call for professional help.
Fill the traps
Plumbing fixtures use water traps to prevent the gas from escaping into the home. If the gas is noticed in a seldom-used bathroom or is escaping from a floor drain in the basement, the problem is often that the water from the trap has evaporated. Use a pitcher to pour about 1 gallon of water into the trap to fill it. Repeat twice per month in order to eliminate future problems.
Check for leaks
If water is leaking around the sink, tub or toilet, sewer gas is also able to escape. If there are leaks under the sink, tighten the slip-joint connectors to stop the leak. If there is water leaking around the toilet, a failed wax ring may require replacement.
Look for clogs
Sewer gas smells sometimes indicate an impending sewer backup. Make sure toilets are flushing correctly and sinks are draining normally. If you note a problem, there could be a clog in the line. If the home uses a septic tank, the smell might indicate it's time for pumping.