Types of Systems

Class 1

Privies: “porta-potty”(portable privies) , outhouses (earth pit privies), vault privies

  • For human waste only
  • Typically in either remote or temporary locations

Class 2

Greywater Systems

  • Can only be used for the treatment and disposal of grey water (no human waste) from plumbing fixtures such as kitchen sinks, bathtubs, washing machines etc.

Class 3


  • Used for the treatment of sanitary sewage from a Class 1 system
  • Usually discouraged because the human waste will quickly clog the soil particles, and slow down its operation
  • Have a short life and are not recommended unless all other possibilities for treatment have been rejected

Class 4

Leaching beds

  • Most common class for residences
  • Consists of tank and a leaching bed, and sometimes a treatment unit
  • Tank: has two or more compartments where solids settle and bacteria begin treatment process
  • Leaching bed: constructed as an absorption trench or a filter bed, effluent flows downward into the soil and is treated biologically by microorganisms in soil
  • Treatment unit: an addition to a septic tank to provide extra treatment to effluent before it enters the soil

Class 5 Systems

Holding Tanks

  • “Holds” sewage until capacity is reached and tank is pumped
  • May be used only on a temporary basis or when the installation of a class 4 is considered impracticable

Types of Class 4 Systems

Pipe and Stone Trench

Distribution pipes are covered in septic stone in separate trenches that each allow effluent to flow downwards into soil. Requires the most space.


Filter Media BedsĀ 

Similar to Pipe and Stone trenches, but distribution pipes are not covered separately in trenches. Instead, the pipes are set in a common layer of stone. May be used on sites where area is an issue, or where natural features minimize the available leaching bed area.


Shallow Buried Trench

A pressurized system that allows effluent to percolate more quickly into the soil. Can be installed more shallow than other systems, and in soils where effluent takes longer to percolate into. It must receive effluent from a level 4 treatment unit.


Dispersal Beds/Area BedsĀ 

These beds receive effluent from level 4 treatment units and are comprised of a stone layer above an unsaturated sand layer. Similar to a filter bed but with a thinner layer of sand, may also be pressurized.