Venting Technical Information

In most applications, the house roof vent will serve as the “high vent” and a “low vent” is installed at the far end of the treatment bed.  Similar to a chimney, as light wind moves across the high vent opening, air is drawn in through the low vent, up through the system and out of the high vent.  The low vent can be disguised or remoted, minimizing visual impact.  (See  remote venting below and venting disguises.)


Please reference your state specific design and installation manual for venting suggestions and requirements.  The following are general venting guidelines:

  • Adequate ventilation is essential to the proper functioning of the Advanced Enviro-Septic™ (AES) Treatment System and the Enviro-Septic® Wastwater Treatment System.
  • Vent openings must be located to ensure the unobstructed flow of air through the entire AES or Enviro-Septic® System.
  • High and low vents are required for all systems.
  • The low vent inlet must be a minimum of 3 ft. from final grade.
  • One 4 in. low vent is required for every 1,000 ft. of AES or Enviro-Septic® pipe.
  • A single 6 in. diameter low vent may be installed instead of three 4 in. diameter low vents.
  • The roof (house) vent is the “high vent” in gravity systems.
  • The diameter of the vent manifold must match the vent stack diameter.
  • Do not remove vents.  Contact your system designer for venting options.
  • We do not recommend the use of charcoal filters on any vents to eliminate odor. If the system is properly vented a charcoal filter is not needed.  In the rare event there is an odor issue, it should be investigated and the root cause(s) determined.  If a positive draft has been confirmed, remotely locating the vent(s) may be the solution (see remote venting below). FAQ
Vent Manifold

Vent Manifold

Vent Locations

Vent locations depend upon the type of system.

Gravity System vent locations:

  • High and low vent openings must be separated by a minimum of 10 vertical feet.
  • Low vents should be a minimum of 3 ft. high or above snow line.
  • A low vent through an offset adapter is installed at the end of each row, section or basic serial bed.  A vent manifold may be used to connect the ends of multiple sections or rows.
  • The house (roof) vent functions as the high vent as long as there are no restrictions or other vents between the low vent and the house (roof) vent.
  • Roof vent diameter must be a minimum of 3 in., 4 in. recommended.
  • Sch. 40 PVC or equivalent should be used for all high vents.

Differential venting is a method of venting an AES or Enviro-Septic® System utilizing high and low vents, typically when a pump is being used to gain elevation to the field.  Differential venting would also be used any time there is an air obstruction between the low vent and the house roof vent.

Pump System vent locations (Differential Venting):

  • High and low vent openings must be separated by a minimum of 10 vertical feet.
  • The high and low vents should be of the same capacity.
  • A low vent is installed through an offset adapter at the end of each row, Section or Basic Serial Bed.
  • Low vents should be a minimum of 3 ft. high or above snow line.
  • Alternatively, the low vent may be attached to the d-box and the high vent may be attached to the end of the last AES or Enviro-Septic® row.  If this configuration is used in cold climates, the d-box must be insulated to prevent it from freezing.
  • A high vent is installed through an unused d-box outlet (see diagram below).
  • Sch. 40 PVC or equivalent should be used for all high vents.
  • All high vents should be at least 4 in. in diameter.
  • All vents higher than 3′ should be anchored.

Differential Venting for Pump Systems

Remote Venting Alternative

Vents can be located to a remote area of the site where they can be virtually invisible.  This involves nothing more than running a length of PVC underground away from the system to a spot where the vent is less noticeable: past the tree line, next to a tree or light pole, behind the garage, wherever it no longer creates an eyesore.

Remote Venting Schematic

Remote Venting Schematic

By-Pass Venting Alternative

By-Pass Venting is a procedure used with the AES or Enviro-Septic® Wastewater Treatment Systems that is an acceptable alternative to differential venting, approved in the State of New Hampshire only. It may be used to retrofit existing systems or in new construction to eliminate the existing pump chamber vent and the high vent attached to the AES or Enviro-Septic® field. (View the approval letter and illustration.)

Important note

The By-Pass venting method may not be used in gravity fed situations (to ensure that solids do not have an open path to the field).

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