Sewage gas, a byproduct of decomposing organic waste, is a mixture of gases that can pose health risks. Understanding its composition, effects, and how to address its presence is important for a healthy indoor environment.
Understanding Sewage Gas
Sewage gas forms from the anaerobic decomposition of organic matter in sewage systems. This anaerobic process generates various gaseous compounds. The main components include hydrogen sulfide, methane, ammonia, and carbon dioxide. While some are odorless, hydrogen sulfide causes the characteristic “rotten egg” smell. The concentration and mixture of these gases can vary depending on sewage composition, temperature, and pH.
Health Effects of Exposure
Sewage gas exposure can cause various health effects, with symptoms varying by gas concentration and exposure duration. Low-level, prolonged exposure may cause symptoms such as headaches, nausea, fatigue, eye irritation, sore throat, and dizziness. These milder symptoms often resolve once exposure ends.
Higher concentrations, especially of hydrogen sulfide, can cause more serious effects. At elevated levels, hydrogen sulfide interferes with oxygen systems, potentially causing loss of consciousness, respiratory distress, or death. Methane, while not directly toxic, can displace oxygen in enclosed spaces, leading to suffocation. Ammonia can irritate eyes, nose, and throat, and is toxic at high levels.
Identifying Sources of Sewage Gas
Several issues can allow sewage gas to enter a building. One frequent cause is a dry P-trap, the U-shaped bend in a drainpipe designed to hold water and create a seal against gases. If a drain is not used regularly, the water in the P-trap can evaporate, removing this protective barrier.
Cracked or broken sewer pipes can also provide a direct pathway for gases to escape into a home. Plumbing vents, which extend through the roof to allow gases to exit and regulate pressure, can become blocked by debris or improperly installed, leading to gas buildup indoors. Loose toilet seals, such as the wax ring, can allow gases to seep out. Issues with the main sewer line or septic tank, such as blockages or leaks, can also contribute to sewage gas intrusion.
Steps to Take and Prevention
If sewage gas is suspected, immediate action is necessary. The area should be ventilated by opening windows and doors to allow fresh air to circulate. Occupants should evacuate the immediate area, especially if symptoms are present. Contacting a professional plumber is necessary to diagnose and repair the source of the leak, as many issues require specialized tools.
Preventative measures reduce the likelihood of sewage gas entering a home. Regularly run water in all drains, including rarely used sinks, showers, and floor drains, to keep P-traps filled and maintain the water seal. Pouring mineral oil into infrequently used drains after filling the trap can slow water evaporation. Regular maintenance, like cleaning drains to prevent clogs and inspecting plumbing for leaks, contributes to a well-sealed system. Ensure plumbing vents on the roof remain clear of obstructions, like leaves or debris, for proper ventilation.