Sewer or septic gases and odors traced to building drain or vent piping defects:
Tthis article describes how to diagnose, find, and cure odors in buildings caused by leaks or other defects in the building drains or sewer line - leaks that make sewage smells or sewer gas smells or "gas odors" in buildings with a focus on homes with a private onsite septic tank but including tips for owners whose home is connected to a sewer system as well.
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Watch out: Because sewer gas contains methane gas (CH4) there is a risk of an explosion hazard or even fatal asphyxiation. Sewer gases also probably contain hydrogen sulfide gas (H2S) In addition some writers opine that there are possible health hazards from sewer gas exposure, such as a bacterial infection of the sinuses (which can occur due to any sinus irritation).
At left is a sewer line leak in a building crawl area.
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Sewer gas source: check for a cap left off of a sewer line cleanout:
In the page top photograph our client is pointing out an open sewer line in the basement of a home she was purchasing. The cap had been left off of a cleanout port where main waste line exited the building.
See Building drain odor source for more details about odors coming from plumbing drains - clues that may be more likely to appear in cool or cold weather. Also see our broad-scope article on diagnosis and cure of sewer gas and septic odors: Sewer Gas Odors diagnosing, finding, and curing septic tank and sewer line smells.
Also see ODORS GASES SMELLS, DIAGNOSIS & CURE for procedures to diagnose and cure all kinds of odors in and around buildings.
What makes the smell in sewer gas? Sewer gases are more than an obnoxious odor. They are also explosive and they may carry bacterial or pathogenic hazards too. Depending on the sewer gas source and other factors such as humidity and building and weather conditions, mold spores may also be present in sewer gases.
We discuss plumbing vents as sources of sewer gas odors separately at Plumbing Vent Defects.
We discuss plumbing fixtures, such as loose toilets, as sources of sewer gas odors separately
Sewer Gas Source: inspect the building drains and gas lines for leaks:
Plumbing drains and traps may smell regardless, as they are usually a reservoir for organic debris.
Remember that a building drain can be leaking inside of a wall or ceiling cavity without showing up as a wet spot or mold.
If the plumbing fixture or drain "gurgles" or makes funny noises when it is draining, or if you hear gurgling noises at some fixtures, say a sink or tub when nearby fixtures are draining, we would certainly suspect that the fixture is not well vented or may not be vented at all.
If you suspect that odors are due to a problem with the building drains but you cannot find a drain line leak nor an open drain cleanout cover, take a look
The sewer gas odor may be coming not from a wet building drain (discussed just above) but from the dry or vent portion of a building's drain-waste-vent system.
CHINESE DRYWALL HAZARDS discusses Chinese drywall odors, sulphur smells, and corrosive outgassing hazards in buildings. Major costs to remove this product, repair or replace electrical wiring, plumbing, and HVAC components may be involved, and there may be immediate safety hazards due to damaged smoke detectors or carbon monoxide detectors in buildings where Chinese drywall outgassing has caused damage.
But on occasion we trace a sewer or septic gas odor to a hidden leak in a drain or vent line passing through building walls or ceilings.
At left our photo illustrates how hidden vent piping leaks may be lurking in an old building, a new building, or in one that has been renovated.
When the installer needed to extend the plumbing vent and drain line to an upper floor of this 1920's home, s/he simply broke open a cast iron vent pipe that was in a lower floor bathroom. There the "plumber" jammed a plastic ABS drain line into the open cast iron waste or vent pipe.
Our pen points out that this connection was certainly not sealed, and that sewer gases or septic gases were readily passing up the vent and/or drain line, into the building walls, and into the occupied spaces.
Continue reading at PLUMBING VENT DEFECTS & NOISES or select a topic from the More Reading links shown below.
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Frequently Asked Questions (FAQs) about plumbing drain odors
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