Actually, sewer gas is mostly methane which is odorless but it's almost always mixed with other gases, the most common of which is hydrogen sulfide which has a rotten egg smell. Hydrogen sulfide comes from decomposing organic matter.,
The most common cause of sewer gas smells in your house is a leak in your plumbing. You'll want to prevent even small leaks to avoid major plumbing repair costs. Sewer gas smells could be coming from your pipes either because they weren't installed properly or were damaged.Feb 11, 2022
Sewer gas has a very distinct odor like gasoline that is easy to detect and associate. It gives off a sulfuric type odor that smells more like rotting food.
A regular sewer-gas smell is just a bad stink with a definite odor of feces and sometimes a rotten-egg (hydrogen sulfide) smell and/or a moldy mustiness too.
The principal risks and effects associated with exposure are: Hydrogen sulfide poisoning. Exposure to low levels of hydrogen sulfide causes irritation of the eyes and respiratory tract. Other symptoms include nervousness, dizziness, nausea, headache, and drowsiness.Jan 11, 2021