Septic Problems - Septic Smell Outside

Septic Smell & Odor Outside Your House

Septic smell & odor outside the house may occur occasionally and typically does not last long.  Under certain weather conditions, the gases from the roof vent may be pushed closer to the ground (nose level) and we notice a smell or odor.  These odor (smell) events can occur with a healthy septic system and may not indicate a problem. 

Frequent, strong, or persistent septic smell or odor outside the house may indicate a septic system problem.

Causes of Septic Smell or Odor Outside the House

Frequent, strong, or persistent septic smell & odor is not normal and may come from the following sources:

Roof vent that does not provide adequate dispersal of odors. The following options may fix this: 

  • The easiest fix is to raise the roof vent by adding an extension. Extension piping should be same diameter as the existing vent. A higher roof vent will experience higher wind speeds that draw the septic gas out more rapidly, provide better mixing, and better dispersal of the septic smell or odor. 
  • A small wind turbine designed for roof vents can also provide better mixing and dispersal of septic smell and odor.
  • An electric roof vent fan can also be used to force the gases out more often and at higher speeds  These also come in solar powered versions.
  • See also Advanced Septic Venting & Odor Control.
  • Frequent, strong, and persistent odors coming from a roof vent may be due to septic system chemistry.  See discussions in the Septic Advisor Blog regarding Septic Odors.
  • Improvements in odor control may also be a benefit of using a septic tank aerator; see Septic Tank Aerators.

Septic smell & odor from the drain field (yard) vent.  These are sometimes called a "candy-cane" vents. Normally, the roof vent should be drawing the septic gases up through the house plumbing with the ground vent supplying fresh air into the system.  The following approaches may help resolve odors emanating from yard vents:

  • Smell & Odor from septic yard vents occur whenever there is a large flow.  Large flows may come from draining a washing machine or a bath tub.  These large flows can rapidly displace a large volume of gas from the septic tank or drain field.   These situations are more problematic if there is an obstruction to venting within the septic system.     Have a septic system professional check for obstructions to venting at the septic tank and D-box.
  • A yard vent is producing frequent septic smell & odor.  This may be fixed by improving the roof vent (see above) or by adding an extension on the septic yard vent.  A higher septic yard vent will allow septic gases to mix with higher wind speeds and disperse more rapidly.  Please note that persistent odors from a septic yard vent may indicate more serious problems with the septic system that may require more extensive repair.  Contact a professional septic system designer/inspector to diagnose the problem.
  • See also Advanced Septic Venting & Odor Control.
  • A past discharge of sewage to the ground (e.g. from a broken pipe) can leave a long term septic smell or odor at the site. Odor removal and disinfection can be most easily accomplished by a generous application of lime to the contaminated area and covering the site with clean soil. 

    Recurring discharge of sewage to ground surface from drain field back-up or other surfacing of wastewater. Contact a septic system design professional.  You should be reading the section called Septic Repair.

    WARNING: Surface discharge of wastewater represents a serious health and safety risk to you, your children, and your neighbors.  Call a local professional to diagnose your problem and advise you regarding repairs.  Many people understand the risks of direct contact with the sewage.  However, many people fail to recognize the health threat posed by insects.  Flies are a common disease vector.  Flies land on the contaminated soil, then land on people, pets and food; transferring disease organisms from one to the other.