Signs & Symptoms of Sewer Gas

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Sewer gas is a foul-smelling combination of gases with a predominant presence of methane gas. It is produced by decaying organic material, residential waste and industrial waste, all often found in the sewage system.

These dangerous gases, when breathed in, can eventually suffocate the victim to death. They are also highly flammable. A byproduct of sewer gas can also be carbon monoxide, which is odourless, colourless and deadly.


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Sewer gas is colourless but it does have a very distinctive, unpleasant odour. Some people have described it as the smell of "rotten eggs." If you believe that you smell sewer gas, get out of the building immediately before making your plans to track down the source. Another odour that may be hard to identify would be that of a gas leak. In both instances, you are in a potentially hazardous environment, and it is essential that you leave the premises as soon as possible.


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Sewer gas can cause a variety of symptoms that could be confused with other illnesses, such as the flu. Unlike the flu, the presence of sewer gas is an immediate danger that can be catastrophic the longer the victim is exposed to it.

The various symptoms include: headache, nausea, lightheadedness or dizziness, disorientation, depression, hallucinations, convulsions, loss of consciousness and finally death. Interestingly, some reports of "ghost sightings" have actually proven to be the result of the person's undetected exposure to sewer gas.


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Remove all people and pets from the vicinity, first, to assure their safety. Next, eliminate the most compelling danger: a possible fuel gas leak. If you believe that there may be a gas leak, you must leave the building immediately. There is a looming risk of explosion. Call the Fire Brigade and your local gas provider for assistance.

Determining if the smell is caused by sewer gas begins with tracing the source of the smell. Areas that are suspect are: sewer or septic piping, toilets with a bad seal, drain traps, water heaters, swamps or marshes, private water supplies. In all cases, it is important to call in a professional to properly eradicate the problem and restore a safe environment.


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Learn proper plumbing maintenance. Drainage outlets that are seldom used in a home are more likely to become a hazard, if not properly maintained. Run water down the drains of laundry sinks, floor drains in basements and garages, guest bathrooms that are used less often, and flush toilets that are also not used much. Check pipes that lead to vents on your roof to be sure that leaves and other debris, such as bird nests or bee hives, are not clogging the air flow. Replace any old or corroded piping and deteriorating seals.

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