Rotten Egg Smell in My Closet

What is Sewer Gas

• Sewer gas is formed during the decomposition of household or industrial waste. Because of this, sewer gas is actually a combination of several toxic and nontoxic gases. Hydrogen sulfide, ammonia, methane, carbon dioxide and nitrous oxides are common components of sewer gas. The gas can enter homes through vents, drains and cracks in the foundation.

Locating the Source

• The first step for resolving a sewer gas leak is locating the source. In most cases, your sense of smell will lead you to the source of the problem. However, if the gas is emanating from inside a wall or seeping through your foundation, it can be difficult to trace. Under these circumstances, it may be advisable to consult a plumber. In some cases, a smoke test is used to determine the location of the leak by forcing an artificially created smoke through the pipes.

Possible Causes and Remedies

• Every water drain in your home should be equipped with a trap and vent. Improper venting and inadequate drain traps may allow sewer gas to escape. Broken toilet seals are another frequent source of sewer gas. An air leak in the wax seal or rotted wood surrounding the toilet may create a portal for gas to enter. A capable homeowner may be able to repair these issues. However, it may be best to consult a plumber. If the smell is most noticeable around a sink, debris may be trapped in the inner chamber of the plumbing. This is where the water is routed to prevent an overflow. Pouring a strong cleanser or bleach down the small hole located inside the bowl near the upper rim may eliminate the problem. One of the most common causes for sewer gas is a dry trap. All drains leading to a sewer system have a "P" shaped trap that is typically full of water. However, if the drain is seldom used, the water may evaporate and eliminate the seal, allowing sewer gas to enter your home. This problem is easily remedied by pouring water down the drain.

Dangers

• Prolonged exposure to sewer gas can lead to serious health and safety issues. Exposure to low levels of hydrogen sulfide can cause eye irritation, nausea, dizziness and drowsiness. While hydrogen sulfide is easily recognized by its rotten egg odor, exposure to high levels could impair your sense of smell, and the inability to recognize the symptom may lead to loss of consciousness and death. High doses of methane gas in an enclosed area could significantly reduce the amount of oxygen in the air. This may cause nausea, dizziness, and in extreme cases, death by asphyxiation. Always take precautions whenever a sewer gas leak is suspected. Methane and hydrogen sulfide are extremely flammable and high levels of the gases may be explosive. Do not light any flames in suspected sewer gas areas.