Hydrogen Sulfide Gas Odors in Buildings - overlooked sources
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Hydrogen Sulfide Gas H₂S Odors, causesl, sources, & hazards in buildings
Check these often overlooked sources of hydrogen sulfide gas, sewer gas, or sewage or septic smells & rotten egg or sulphur like odors
Other causes of sewage odors, septic odors, sewer gas, rotten egg, or other indoor gas odors
How to track down the sources & causes of sewer gas smells
Sewer gas smell diagnosis - plumbing checklist
Septic gas smell diagnosis - septic system checklist
Questions & answers about often overlooked causes of hydrogen sulfide gas smells or H₂S or sewer gas or septic odors in buildings

Don't overlook these possible sources of sewer gas smells or hydrogen sulfide gas odors: here are the causes, sources, & cures for often overlooked sources of sewer gas smells. This article series explains how to diagnose, find, and cure odors in buildings including septic or sewage or sewer gas smells or "gas odors" in buildings.

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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). Hydrogen is extremely flammable (easily set fire or explodes).

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.For details about exposure to various toxic and irritating gases see GAS EXPOSURE LIMITS & STANDARDS and TOXIC GAS EXPOSURE EFFECTS.

See ODORS & SMELLS DIAGNOSIS & CURE for procedures to diagnose and cure all kinds of odors in and around buildings. Also see Wet Weather or Cold Weather Septic Odors or Sewage Odor Diagnosis & Repair Guide for additional odor tracing and cure advice for odors occurring during wet or cold weather.

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Other Causes of Odors Blamed on a Sewer, Septic System, or Building Water Supply. Hydrogen Sulfide or Rotten Egg Smells: causes, dangers, advice

Septic system odors may occur from a few other common conditions which you may not have considered:

Inspect the building water heater: if the "sewer gas smell" is noticed particularly when hot water is being run at a sink, tub, or shower, have your plumber check for a bad water heater sacrificial anode.

This rod is intended to slow corrosion in the water heater tank but when the anode deteriorates it can cause a "rotten egg" smell in the hot water supply which may be mistaken for sewer gas. We discuss the hot water tank sacrificial anode and dip tube in more detail at Check the Sacrificial Anode & Dip Tube of Your Water Heater Tank.

Watch out: Hydrogen sulfide gas is potentially explosive, can catch fire, and if it is mixed with or originating from sewer gases, it may contain pathogens or be harmful to humans and othe ranimals. But in addition, water heaters can be a source of this sulphur or rotten egg smell due to bacterial growth or anode deterioration as we just cited. Water heater manufacturers, including American Water Heater Co., advise,

Hydrogen gas is produced in a hot water system served by this heater that has not been used for a long period of time (2 weeks or more). Hydrogen is extremely flammable. To reduce the risk of injury under these conditions, it is recommended that the hot water faucet be opened for several minutes at the kitchen sink before using any electrical appliance connected to the hot water system. When hydrogen is present, there will be an unusual sound such as air escaping through the pipe as the water begins to flow. There should be no smoking or open flame near the faucet at the time it is open. [5]

More details about dangers of hydrogen sulfide gas exposure are at Hydrogen Sulfide Gas H₂S Exposure and at Hydrogen Sulfide Gas Danger
Check the building water supply: if the "sewer gas smell" is a "rotten egg smell" and if it is noticed particularly when hot or cold water are being run at a sink, tub, or shower, your water supply may contain excessive hydrogen sulphide or H₂S.

This is not likely to be the case if you are on a municipal or community water supply but could occur if your water is supplied by a private well. Have the water tested for sulphur and H2S. If this condition is confirmed, the H2S is not a health concern but remains an aesthetic one.

It can be corrected by installation of a proper water treatment system such as a chlorine injection system, a potassium permanganate filtration system, or by other methods. More information about causes of and cures for hydrogen sulfide odors in water is at Identifying Odors in Drinking Water.
U.S. Army Field Manual FM-8-285-Noxious_Chemicals discusses Ammonia, Carbon Monoxide, Hydrogen Sulfide, Oxides of Nitrogen, Hazards caused by fire
Use of improper or excessive cleaning chemicals in the building, or perhaps excessive use of antibiotics (such as by a nursing home served by a septic tank and whose residents consume a lot of antibiotics) can kill off bacteria in the septic tank. This is an unusual condition unlikely to occur in a normal homeowner environment.
For help in tracking down sulphur or sewer odors to their source: also see SMELL PATCH TEST to Track Down Odors and SULPHUR & SEWER GAS SMELL SOURCES

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Questions & answers about often overlooked causes of sewer gas or septic odors in buildings

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Use links just below or at the left of each page to navigate this document or to view other topics at this website. Green links show where you are in our document or website.

SEWER GAS ODORS - see detailed links at page left

SEWER GAS ODORS in COLD WEATHER - see detailed links at page left

SMELL PATCH TEST to Track Down Odors
SULPHUR & SEWER GAS SMELL SOURCES

[1] Thanks to Slade Franklin for the reminder that a leaky wax ring at a toilet can lead to septic odors in bathrooms. 11/2007
[2] Thanks to J.V. (privacy protected) for the reminder to make a detailed inspection of the plumbing vent system when sewer gas odors are present. 07/2008
[3] Thanks to Roger Hankey & Cheryll Brown, www.hankeyandbrown.com, ASHI home inspectors in Minnesota, for the deteriorated transite pipe gas flue vent photograph and comments. Mr. Hankey is a past chairman of the ASHI Technical Committee, serves as co-chairman of ASHI legislative committee, and has served in other ASHI professional and leadership roles. 7/2007.
[4] U.S. Army Field Manual FM-8-285-Noxious_Chemicals discusses Ammonia, Carbon Monoxide, Hydrogen Sulfide, Oxides of Nitrogen, Hazards caused by fire,
[5] "Residential Electric Water Heater Installation Instructions and Use & Care Guide", American Water Heater Co., October 2001, American Water Heater Co., Johnson City, TN, [manufacturer of residential & commercial water heaters, also manufacturer of Polaris/Commercial water heaters], Tel: 800-999-9515, web search 1/12/2012, original source: americanwaterheater.com/support/manuals/res-elect.pdf [copy on file]
Cold Weather Septic Odors or Sewage Odor Diagnosis for additional odor tracing and cure advice focused on sewer gas odor tracking in cold or wet weather.
Drain Noises: may indicate defective or clogged plumbing: how to diagnose and cure drain sounds

The Septic System Information Website home page for this topiccalculating septic tank volume from size measurements
Septic Tank/Soil-Absorption Systems: How to Operate & Maintain [ copy on file as /septic/Septic_Operation_USDA.pdf ] - , Equipment Tips, U.S. Department of Agriculture, 8271 1302, 7100 Engineering, 2300 Recreation, September 1982, web search 08/28/2010, original source: http://www.fs.fed.us/t-d/pubs/pdfimage/82711302.pdf.
Pennsylvania State Fact Sheets relating to domestic wastewater treatment systems include

Pennsylvania State Wastewater Treatment Fact Sheet SW-161, Septic System Failure: Diagnosis and Treatment
Pennsylvania State Wastewater Treatment Fact Sheet SW-162, The Soil Media and the Percolation Test
Pennsylvania State Wastewater Treatment Fact Sheet SW-l64, Mound Systems for Wastewater Treatment
Pennsylvania State Wastewater Treatment Fact Sheet SW-165, Septic Tank-Soil Absorption Systems
Document Sources used for this web page include but are not limited to: Agricultural Fact Sheet #SW-161 "Septic Tank Pumping," by Paul D. Robillard and Kelli S. Martin. Penn State College of Agriculture - Cooperative Extension, edited and annotated by Dan Friedman (Thanks: to Bob Mackey for proofreading the original source material.)

Books & Articles on Building & Environmental Inspection, Testing, Diagnosis, & Repair

Our recommended books about building & mechanical systems design, inspection, problem diagnosis, and repair, and about indoor environment and IAQ testing, diagnosis, and cleanup are at the InspectAPedia Bookstore. Also see our Book Reviews - InspectAPedia.
Inspecting Septic Systems: Online Book, Inspection, Test, Diagnosis, Repair, & Maintenance: our Online Septic Book: Septic Testing, Loading & Dye Tests, Septic Tank Pumping, Clearances, details of onsite waste disposal system inspection, testing, repair procedures.
Builder's Guide to Wells and Septic Systems, Woodson, R. Dodge: $ 24.95; MCGRAW HILL B; TP; Quoting from Amazon's description: For the homebuilder, one mistake in estimating or installing wells and septic systems can cost thousands of dollars. This comprehensive guide filled with case studies can prevent that. Master plumber R. Dodge Woodson packs this reader-friendly guide with guidance and information, including details on new techniques and materials that can economize and expedite jobs and advice on how to avoid mistakes in both estimating and construction. Chapters cover virtually every aspect of wells and septic systems, including on-site evaluations; site limitations; bidding; soil studies, septic designs, and code-related issues; drilled and dug wells, gravel and pipe, chamber-type, and gravity septic systems; pump stations; common problems with well installation; and remedies for poor septic situations. Woodson also discusses ways to increase profits by avoiding cost overruns.
Country Plumbing: Living with a Septic System, Hartigan, Gerry: $ 9.95; ALAN C HOOD & TP; Quoting an Amazon reviewer's comment, with which we agree--DF:This book is informative as far as it goes and might be most useful for someone with an older system. But it was written in the early 1980s. A lot has changed since then. In particular, the book doesn't cover any of the newer systems that are used more and more nowadays in some parts of the country -- sand mounds, aeration systems, lagoons, etc.

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Other Causes of Odors Blamed on a Sewer, Septic System, or Building Water Supply. Hydrogen Sulfide or Rotten Egg Smells: causes, dangers, advice

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