Sewer gas leak or contamination test procedures:
This article describes how to How to Test for & Trace Sewer Gas Smells and Septic Tank Odors in a Building or how we might trace "gas odors" in buildings with a focus on homes with a private onsite septic tank or for owners whose home is connected to a public sewer system as well. What makes the smell in sewer gas? Sewer gases are more than an obnoxious odor.
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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). 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.
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Tests for sewer gas or septic odor gas leaks: When looking for gas leaks and tracking gas smells, one method to get more precise is to use an instrument sensitive to a broad range of combustible organic gases.We use a TIF 8800 combustible gas analyzer set at its most sensitive setting to sniff for gas leaks.
Our photo at above left illustrates a type of hidden and subtle source of sewer gas odors in buildings: defects in the building drain, waste, or vent piping that are hidden in wall or ceiling cavities.
This particular leak is discussed at DRAIN PIPING & SEWER ODORS .
This instrument will respond to a very wide range of volatile organics, including pipe dope on a plumbing joint, so be careful.The TIF8800 will also respond a little to the gases found at almost any plumbing drain since the trap is often producing some organic gases.
But if you find that there is one drain that responds unusually strongly, or if you find a leak in a fuel gas line, you've found a problem to correct before going further.Many home inspectors have this tool and can be hired to apply it carefully in your home, or it may be less costly (than hiring an inspector) to just buy the tool itself.
Also see TIF 8800 GAS DETECTOR for a detailed procedure of how this instrument is employed and for a list of gases to which it will respond.
Watch out: The use of most test instruments gives only an instantaneous indicator of a substance that is present at the time of the test and in the location tested. Tests for individual substance or even individual classes of substances are never a complete assurance of building conditions, as other substances not within the scope of the test may be present.
And instrument tests are never a sure indicator that hazardous substances are not present or have not been present at other times or under different building conditions. Never rely only on the results of test instruments when examining a building for unsafe conditions such as gas leaks.
Expert visual inspection of the building exterior, interior, and mechanical systems as well as an understanding of the building's damage, leak, and repair history and of the vulnerability of particular construction designs and materials are all important considerations when evaluating the condition of a structure.
Certainly there are quite a few (often more expensive) instruments that can test for combustible gases, and there are gas-specific tests that address methane-only. For general use a broad-spectrum test instrument such as the TIF8800 discussed here offer the advantage of sensitivity to a wide range of gases, increasing the chance of detecting a concern when the instrument is used, and also increasing the chance of confusion about just what gas is present.
At TIF 8800 GAS DETECTOR we provide details about the use of the instrument described in the article above.
At Drager GAS DETECTORS we describe a simple pump instrument that can, by selecting the proper detector tube, test for a very large range of individual gases at various concentrations.
Other types of gas detection instruments are discussed at GAS DETECTION INSTRUMENTS
For readers interested in monitoring specifically for methane gas, perhaps as an indicator of sewer gas leaks, take a look at the Xintex Methane Gas Detector S2B-M-X, described by its manufacturer as follows:
The Xintex® Methane Gas Detector / Monitor, Model S2B-M-X-Display-D, constantly monitors the level of highly explosive methane and goes into alarm prior to a dangerous situation occurring. This advanced micro-processor, state of the art, Methane Gas Detector is incorporated into the design and re-design of vehicles using CNG or LNG as a fuel.
The company offers other methane gas detection systems as well, including sensors designed to react to specific elevated levels of methane and natural gas.
Watch out: when buying any gas detection instrument be sure to compare the detection and reporting range of the instrument with the level of concern that you need to address. Otherwise dangerous conditions may exist without detection.
(May 14, 2016) Anonymous said:
How do you detect and measure concentrations of sewer gas?
Because of the significant variation in the rate, density, concentration and composition of sewer gas that might be leaking into a building, concentration is not measured by the typical investigator. Rather she uses a broad-spectrum combustible gas detection instrument such as the TIF8800 discussed in these pages (TIF 8800 GAS DETECTOR) - with the caveat that that sort of instrument will respond to a wide range of combustible gases. It's the use of the tool in proper context that makes it a reliable and appropriate method.
If for technical reasons you needed to know the concentration of sewer gases, or perhaps of just methane - a primary component - there are more costly and sophisticated electronic instruments that can do that.
Similarly, some natural gas service companies use a quantitative measurement rather than mere detection.
Continue reading at TIF 8800 GAS DETECTOR or select a topic from closely-related articles below, or see our complete INDEX to RELATED ARTICLES below.
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(Oct 3, 2012) Rudy said:There is a foul odor around our house the main problem finding the source the intermittent occurrence of the odor. This odor does not smell like anything ever smelled by myself or my wife. While windows are open the odor will come from outside through mostly back room windows. When I say odor I mean it knows your socks off, forcing us to close all windows. Sometimes it will last for minutes other times for longer periods. We can only say it happens towards the start of evening or late night. We have had Fire department come by to help but it is not always present and calling them draws valuable resources from the city. Can you help?
See if either of these articles will help you track down the smell source:
Or start with our odor diagnosis suggestions found at the home page for this topic ODORS GASES SMELLS, DIAGNOSIS & CURE
After reviewing your site discovered a reference to height requirement of sewer vent pipes. The recommendation states these pipes should be at least 6 to 12 inches high. Decided to head outside and see what mine were and immediately a question popped into mind. Are we talking 6 to 12 inches from installed location or highest point on the roof.
Also I live on a slight hill so my house sits between two others, the higher elevation home is about 10 to 12 feet higher while the lower home is only about 3 feet below our home. I mention this only to see if this would affect the vent sewer pipe height requirement.
The vent pipe height recommendation refers to height above the roof surface at the point of penetration of the roof deck. I would add that for freezing climates the vent pipe diameter may be quite important too if we are to avoid drain and vent problems due to frost clogging of the vent or covering of vents by deep snow.
Sure on occasion site factors such as nearby buildings or hills or trees can also generate downdrafts that can blow rooftop-vented sewer gases down to ground level, but in my experience the rooftop vent would not be so likley to be the source of very strong odors right at the building exit door, and your note did not make clear that this is a sewer gas or septic system odor anyway.
Have you looked for signs of a dead animal nearby or even in a crawl area?
(Aug 23, 2012) Kathy Ng said:
What could be the source of foul smell which seem to be coming from the air conditioner ducts and is not prevalent just intermittently?
I have to offer similar advice to the above reply to Rudy, as we've got no information about your building; certainly refrigerant gases are odorless themselves, so more likely your return air intake is picking up smells from some source - or there could be a dead animal in the ductwork; These could be health or safety concerns.
I believe we have a sewer gas problem in our office building. The building owner had a plumber out to investigate and the plumber was useless, saying that it is a dead animal causing the smell and insists that it is not a plumbing problem. Our exterminator, who treats our building on a monthly basis, said that the smell is not a dead animal, not for 4 months. After the plumber investigated, one of our clients, who is an engineer, came into our office for an appointment and as soon as he walked in our lobby, he said “You all have sewage gas leak.”
We informed the building owner of his statement. The owner had someone to come out and dig up the sewer main drain line inside our building, more specifically, our downstairs conference room, which is located next to my office. They found 3 very small wet spots on the drain line. They replaced a small section of piping where the 3 tiny wet spots were and capped an old open pipe; however, the smell is still very much present.
Our office staff has been staying sick with sinus infections and headaches for the past several months. The building owner will not call another plumber to get a second opinion. I would like to know if there is some sort of a device that can detect sewer gases. If so, what type of professional would we call to help us. I have been researching this problem for a month. In order, to get the building owner to seek additional action, I must have on hand to show them. Please help me out if you can.
The staff and I are sick of being sick and smelling this rancid smell. I greatly appreciate your time spent reading this email. If for any reason at all you need to contact me, my office contact information is below. Again, thank you for your time. PS: If this info is useful, our building is over 100 years old and is located in the city (city water/sewer). - S.R. 2/19/2014
Please review the article above to which I referre you by private email. Also let me re-emphasize that while instruments can be helpful in tracking down the most-likely sources of an odor in a building, I would never rely on an instrument alone: without an expert and thorough inspection and without a thoughtful history-taking of the building's plumbing and leak events, occupant complaints, and other factors, an instrumented test risks missing important hazards or conditions.
For example, in the caseyou describe one would want to know the history of sewage backup or spill, what cleaning was performed, what else may be needed, and also whether or not wet areas created a mold contamination problme, and thirdly whether there is some other irritant source in the building.
Reader Question: (Apr 30, 2012) John Rapciak said: I would like to know where i can buy testing equipment or patches, i believe bad or maybe toxic fumes are coming into my bathroom (fan on or off) from my exhaust fan, possibly from my neighbors apt. through their exhaust fan. Will you help! Thank You, John R. 708-466-7819.
Reply: John, to avoid any possible conflict of interest, InspectAPedia does not sell anything. Your question is a bit too broad an approach - what sort of equipment or "patches" are you thinking about? As there are many possible indoor contaminant sources and tests tend to be rather specific, you may have better results by tracking down the odor to its source first. If you hire an expert to perform testing, do not rely on tests alone - be sure that your expert really is one, and that s/he conducts a thorough inspection of the property and its venting system. Gas testing equipment products, brands, manufacturers and sources are listed in this article series both in the articles and in the article references section.
Apr 1, 2014) csaba kovacs said:
there is a smell of hydrogen sulfide from am upstairs bathroom. Last nite was really strong. Do I need a plumber...septic tank service or can I test for it my self.Can I get a tester from somewhere?? Perhaps a rentall place ?? 810-772-9176
For general and highly sensitive testing you can use an instrument like the TIF 8800 GAS DETECTOR - see the link above to an article discussing that instrument, warnings about its sensitivity, and where it can be obtained. Watch out that an instrument in inexperienced hands is not so reliable and could even be dangerous. You might prefer to contact your local health or safety authorities for help.
(June 23, 2014) firstname.lastname@example.org said:
Hello, I am renting a older split home in Gulfport, and have been suffering from headaches since moving in a year ago. Recently an AC man came over, and while checking my AC, he stated loudly Sewer Gas leak, which was coming from my bedroom closet where the back of the AC intake was at. There was a hole leading to the ground and pipes which was boxed in by sheetrock, and the AC guy sealed the point where the pieces met, and left. Any advice would be helpful. Thank you
Certainly you will want to find and fix the leak. Sewer gases are potentially explosive as well as smelly and potentially unsantiary. I'm unclear on what you or your AC guy actually are seeing: an open pipe, a leaky pipe, a blocked drain, or a drain line vent that is leaky or improperly constructed.
Keep in mind that gases leaking near an AC return air vent can be transported throughout a building.
Keep in mind also that even if there is no sewer gas leaks, defective Chinese Drywall outgassing can be mistaken for (and have similar effects as ) a sewer gas leak.
7/22/14 w barnes said:
My wife is presently in a nursing home with very advanced dementia, the building is a Victorian building and her bathroom constantly smells of drains the internal ceiling fan does not work at the moment and does not have any natural ventilation or windows. I have expressed my concern and the home has put it in their jobs -to do book. their repairs take ages so what I would like to ask is there a gas indicator that could go on the wall that if gas is present the chemical makeup would change colour ,something like litmus paper does for acids
At the end of the article above I have added a section on alternative methods for testing for sewer gas.
I have not found a simple test strip or colour changing methane test and it's possible that the instruments we describe may seem costly. An alternative is to ask for a test by an onsite expert who has and knows how to use appropriate equipment.
For monitoring, See our description of the Xintex products above.
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