Cure for sewer smells & odors in or around buildings:

How to find and fix the source of sewer or septic smells & gas odors in or at buildings: common odor sources and how to find and fix them.

Here we provide descriptions of sewage smell sources and list of links to details about steps to take in curing methane gas, sewer gas, or septic gas smells that are traced to these building plumbing or to an onsite septic or cesspool or drywell system.

Remedies for Sewer Odors Caused by Plumbing Defects or Septic System Defects

Watch out: as we show in this home inspection photograpn, locating a return air inlet close to a heating furnace, particularly a gas or oil fired heater may be unsafe, risking drawing combustion gases into the buildings HVAC duct system.

See UNSAFE DUCT OPENINGS for more about picking up un-wanted gases or odors at return air inlets.

[Click to enlarge any image]

Article Contents:

• COMMON SOURCES of PLUMBING ODORS
• DRAIN LINE BLOCKAGE or LEAKS
• BLOCKED DRAIN REPAIRS
• SLOW DRAIN REPAIRS

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.

List of Common Sources of Odors Traced to Building Plumbing Systems

• Abandoned plumbing drains:
  
  Aan abandoned plumbing drain that was simply cut without permanently-sealing the opening in any drain pipes or vent pipes left in place can be a hard-to-spot source of building odors. Below we illustrate the problem.
  
  Taking a quick look beneath a kitchen sink in a dark corner that was hard to see, we saw a rusty rag poking out of the building wall.
  
  An older galvanized iron kitchen sink drain line had simply been cut off when installing a new sink. The remaining drain piping was still connected to the building drain and sewer piping system: sewer gases could enter this home through the opening we illustrate below.
  
  Use the flashlight, Luke!

• Backdrafting in building causing sewer gas odors:
  
  bath or other building exhaust fans may draw sewer gases up from drain piping, especially if there are dry plumbing traps. See
  • BACKDRAFTING & SEWER / SEPTIC ODORS
  • Make sure that bath and other vent fans are properly installed and located
  • Make sure that the building has adequate fresh air intake,
  • Check that there are no dry traps or siphoning traps.
  • Add plumbing venting or vacuum breaker vents (where permitted) to stop trap siphonage if necessary.
• Clogged plumbing traps or drains may result in siphonage of the trap water, then releasing sewer gases into the building.
  • Check for and repair clogged traps or drains. See
  • CLOGGED DRAIN DIAGNOSIS & REPAIR - un-clog the problem traps or drain lines.
  • TRAP SIPHONAGE & SEWER GAS
• Cold weather correlates with sewer odors or slow, noisy drains:
  
   If your sewer or septic odors appear to occur only in cold or freezing weather,you will want to install a larger diameter plumbing vent stack from the roof surface up, or from the attic floor out through the roof (if your attic is un-heated). See
  • SEWER GAS ODORS in COLD / WET WEATHER for more sewage odor diagnostic articles.
• Plumbing traps indoors, smelly:
  
  Special plumbing traps which include a built-in seal against gas backups are available for use in problem locations. We just pour mineral oil into unused traps to prevent evaporation of the trap seal. See
  • PLUMBING DRAIN NOISES
  • PLUMBING DRAIN NOISE REPAIR
  • TRAP SIPHONAGE & SEWER GAS - how loss of water in the plumbing trap releases dangerous & smelly sewer gas
• Plumbing vent diameter or height
  
  Inadequate plumbing vent diameter or height: If it's a plumbing vent diameter problem the solution would be to install a larger diameter vent pipe, eg 2" up through the roof and outside. See
  • PLUMBING VENT BLOCKAGE ODORS - why plumbing vents may stop working in freezing weather
  • PLUMBING DRAIN NOISES - an explanation of plumbing vent requirements, and see
  • PLUMBING VENT DEFECTS & NOISES- diagnostic procedures.
• Plumbing venting Inadequate, incomplete, missing
  
  plumbing drain line venting: if building vent piping is missing or inadequate or improperly installed get advice from a plumber on both stop-gap ("V-200" vacuum breaker vents [photo] from Oakville Stamping & Bending)* or proper (vent piping) repair alternatives.
  
  See PLUMBING DRAIN NOISES for an explanation of plumbing vents, and see PLUMBING VENT DEFECTS & NOISESfor diagnostic procedures.

• Plumbing vent clogged -
  
  Ddue to animals, insect nests, or damaged vent material such as transite piping. Repair or replace the clogged or damaged plumbing vent piping.
• See PLUMBING DRAIN NOISE DIAGNOSIS for more about diagnosing clogged plumbing vents
• See TRANSITE PIPE CHIMNEYS & FLUES for more about plumbing vents made of transite pipe
• See   TRAPS on DRAINS and   PLUMBING VENT DEFECTS & NOISES

• Plumbing Vent location,
  
  Bad: if a building vent is too close to a window or otherwise is delivering gases to occupants, it may be possible to extend or relocate it.
  
  See PLUMBING VENT DEFECTS & NOISES for diagnostic procedures like gurgling drains
• Plumbing vent discharging into the building attic or roof space
  
  Plumbing vents should terminate outside, above the roof level. This defect should be corrected as soon as possible as there are both health and methane gas explosion hazards when sewer gases are vented indoors.
  
  See PLUMBING VENT DEFECTS & NOISESfor diagnostic procedures.

Odors and Plumbing Drain Line Leaks or Blockage Repairs

Diagnose leaks and/or sewer gas odors due to damaged drain or sewer line piping

If a building drain is damaged and leaking the point of damage needs to be found and repaired.

If it's an indoor drain the leak can usually be found by evidence of leaks into the building; if it's an outdoor drain leak, use of a plumbing snake, judicious careful probing, or excavation will be needed.

Sometimes simply lifting a section of sidewalk over a drain or lifting a large stone will disclose a previously unrecognized wet area where a drain line has been broken or damaged.

Our photo (left) shows a source of both sewage odors and a blocked main drain line between a house and its septic tank.

The sewer line was broken when a heavy commercial lawn mower drove over the concrete sidewalk below which the sewer line had been installed.

We replaced the entire drain line between the house and the septic tank and our contractor made sure that the new plastic sewer line was properly protected from damage by bedding it in sand.

 

See SEWER LINE REPLACEMENT for details about installing a new sewer line.

Blocked Drains as a Cause of Septic or Sewage Odors

If building drains are blocked or appear blocked

hire a plumber to snake the drains.

If all drains are blocked or slow,

the plumber might start by snaking out the main drain.

During this process an experienced plumbing power snake handler can tell if the drain line is broken or damaged or clogged by tree roots. If this is the case an excavator and drain line repairs are needed.

See CLOGGED DRAIN DIAGNOSIS & REPAIR

Slow Drains as a Cause of Septic or Sewer Gas Odors

If building drains are not blocked but drainage is slow,

sluggish, smelly, or backing up into the building, an inspection of the septic tank can indicate (by abnormally high level) that the tank inlet baffle or outlet baffle are blocked (or missing entirely), or that the tank outlet to drainfield is backing up, or blocked, or the drainfield not working.

Also see CLOGGED DRAIN DIAGNOSIS & REPAIR

Pumping out or cleaning the septic tank to address an "odor problem"

 probably won't help: while periodic pumpout of a septic tank is important maintenance to protect the drainfield, will never "fix" one of these problems. The cause of blockage or failure needs to be identified and repaired.

We can think of a case, however, where pumping and inspecting the septic tank baffles might help diagnose a sewer gas odor outdoors or in the building. If the septic tank inlet or outlet baffle is partially blocked by the floating scum layer (the tank is past due for cleaning) sewer gases may back up into the building.

See SEPTIC TANK PUMPING SCHEDULE

and for a guide to inspecting septic tank baffles,

see SEPTIC TANK BAFFLES.

...

Continue reading  at SITE WEATHER or NEIGHBOR'S SEWER ODORS or select a topic from the closely-related articles below, or see the complete ARTICLE INDEX.

Or see SEWER GAS ODOR REMEDY FAQs - questions & answers posted originally at the end of this page.

Or see these

Recommended Articles

• DRAIN PIPING & SEWER ODORS - home
• FLOOR DRAIN / TRAP ODORS
• PLUMBING SYSTEM ODORS - home
• SEPTIC SYSTEM ODORS - home
• SEWAGE PUMP ODORS
• SEWER GAS ODORS - home
• SEPTIC / SEWER ODOR SOURCE TABLE
• SEWAGE ODOR SOURCE LOCATION
• SEWER GAS ODORS in COLD / WET WEATHER
• SEWER GAS ODOR REMEDIES
• SEWER LINE REPLACEMENT
• SEWER / SEPTIC PIPE CAMERAS
• SEWER SEPTIC GAS CONDUIT LEAKS
• SEWER SEPTIC ODORS in HVAC DUCTS
• SITE WEATHER or NEIGHBOR'S SEWER ODORS
• TESTS for SEWER GAS INDOORS
• TRACK SEPTIC ODORS to SOURCE
• TRACK SEWER ODOR by WEATHER
• TRAP SIPHONAGE & SEWER GAS
• WATER POLLUTANT SOURCES
• WET WEATHER SEWER ODORS

Suggested citation for this web page

SEWER GAS ODOR REMEDIES at InspectApedia.com - online encyclopedia of building & environmental inspection, testing, diagnosis, repair, & problem prevention advice.

Or see this

INDEX to RELATED ARTICLES: ARTICLE INDEX to PLUMBING SYSTEMS

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Citations & References

In addition to any citations in the article above, a full list is available on request.

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