A/C coil corrosion - Chinese Drywall - US CPSC How to Find & Fix Sources of Sulphur Odors or Sewer-Gases, Rotten Egg Smells & Hazards in buildings

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How to find and fix the source of sulphur odors and smells in buildings: this article and its companions discusse the common sources of rotten egg odors, sulphur odors or sewer gas smells in buildings and traces them to their possible cause.

Examples of sources of sulfur smells in or around buildings include Chinese drywall outgassing, dangerous sewer gas leaks, plumbing vent defects, sulfur in drinking water, water heater bacteria, and more. We describe safety, explosion, and bacterial hazards associated with sulphur gases and sewer gases in buildings. Our page top photo shows a subtle clue that can explain a sulphur odor in buildings: discolored copper piping on the air conditioner cooling coil caused by outgassing from Chinese drywall.

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How to Find & Fix Sources of Sulphur Odors or "Rotten Egg Smells" in buildings Include Smells Associated with Chinese Drywall & Other Causes in buildings

Open sewer cleanout in basement (C) Daniel FriedmanThis article series about building odors discusses the diagnosis and cure of odors from a variety of sources including animals including pets, dogs, cats, or unwanted animals or dead animals, formaldehyde odors in buildings from building products or furnishings, plumbing drains, plastic or vinyl odors from building products, flue gases, oil tanks or oil spills, pesticides, septic odors, sewer gases, and even abandoned chemicals at properties.

The page top photo of blackened corrosion on an air conditioner cooling coil is from the U.S. CPSC warning to fire safety professionals.

Common Sources of Sulphur Gases & Odors in buildings: Causes of "Rotten Egg" Smells

Sulphur odors in buildings are described also as rotten egg smells or even flatulence smells that generally are associated with the presence of hydrogen sulfide (H2S) gas. To track down and cure the source of such odors review the list below. Information about the gas itself and links to hydrogen sulfide exposure limits and health effects are given separately

  • Electrical conduit leaks conducting septic tank gas: a reader has reported septic gases following electrical conduit from septic pumping station into the principal building.
    See Seal Septic Gas Leak Through Electrical Conduit?

  • Chinese drywall contamination can produce dangerous sulphur gases and rotten egg smells in buildings that have driven people from homes, caused costly damage, and in some cases cause health concerns as well.

    • See CHINESE DRYWALL HAZARDS for details about Chinese Drywall problems in U.S. homes. Chinese Drywall outgassing, particularly in homes where drywall was installed in new construction or in remodeling after 2004, creates rotten egg smells & odors, indoor air quality hazards, corrosive outgassing, health hazards, and damage to copper building components such as copper electrical wiring and plumbing - caused by outgassing from Chinese Drywall used in construction in the U.S.
    • Some buildings using Chinese drywall do not present a characteristic sulphur odor but may still have corrosion and outgassing problems
    • There are multiple possible sources of sulphur gases and sulphur odors in buildings
    • Individual sensitivity to odors varies substantially, making odor reports inconsistent, but complaints include headaches, runny noses, and difficulty breathing.
  • Sulphur odors from well water - see
  • Sulphur gases and odors from a failing hot water tank sacrificial anode - see
  • Sulphur gases and odors from a bacterial contamination of a hot water tank, often curable by cleaning and shocking the tank interior with chlorine or bleach.
  • Sulphur odors from defects in the building drain waste or vent piping

    Watch out: if the sulphur odors in a building are due to sewer gas backups, dangerous levels of possibly explosive methane gas could be present. Also, at SEPTIC & CESSPOOL SAFETY we explain that gases produced in a septic tank are dangerous, as a potential source of explosion and as a cause of death by asphyxiation if someone falls into or deliberately enters a septic tank.

  • Sulphur odors from plumbing traps: Sulphur odors or "septic odors" at a kitchen sink may actually be food odors from a garbage disposer that needs cleaning.
  • Sulphur odors from a failing or backing-up septic system - see
  • Sulphur odors originating outdoors - see Site, Weather, or Failing Neighbors
  • Dead animals: Other odors mistaken for sulphur odors, such as a dead animal in building walls or crawl spaces. We also mention human flatulence which also can have a sulphur odor but will normally be episodic and brief in duration.
  • LP Gas or Natural Gas Leak odors: Watch out: some people mistake dangerous, possibly explosive LP gas or natural gas leak odors for sulphur gas or sewer odors.
    See Gas Piping and Tank Defects.

In sum, before blaming drywall for building odors, be sure that the smells are not from another detectable source such as sewer gases or a failing hot water tank anode -
see ODORS, Smells, Gases in buildings-Diagnosis & Cure for details and


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