Conventional anaerobic septic systems provide adequate treatment under many conditions; however, because they discharge contaminated wastewater into the natural environment they depend on natural processes to complete the waste treatment. They require a substantial thickness of free draining soil, and groundwater must be located well below the disposal lines. If these conditions are not met then septic soil conditions and/or groundwater contamination can result. By removing contamination before the effluent is discharged, aerobic treatment expands the conditions under which on-site disposal of residential sewage can be safely performed. Aerobic treatment also allows the use a shallow drip irrigation tube for effluent disposal, which makes it particularly beneficial for replacement of existing systems since the lines can be installed with easy equipment and can be routed to avoid landscaping, driveways, outbuildings and other existing features on developed lots.
Shallow groundwater or bedrock
Septic systems typically require at least 5 feet of soil cover above groundwater or bedrock. Aerobic systems can usually be installed in locations with as little as 24 inches of soil cover. In many cases this distance can be further reduced by installing properly designed engineered fill.
Aerobic systems typically require smaller disposal areas than septic systems. Small lots that are unbuildable with a conventional septic system can become buildable with an aerobic system; a lot that is only suitable for a two-bedroom house can become suitable for three or four bedrooms.
Adverse ground slope.
Slopes that are too steep for conventional septic systems may be suitable for aerobic systems. Also, since gravity flow is not required, the treatment system and drain field can be placed in virtually any convenient location.
Drip lines are highly flexible allowing them to be routed into the corners of lots, beneath narrow planting areas, or around obstructions; making full use of available areas.
Adverse soil types
Aerobic treatment is suitable for a variety of soil conditions that are either too permeable or not permeable enough for a conventional septic system.
Aerobic treatment offers advantages on a developed lot where a backhoe or other earthmoving equipment could cause excessive damage. The shallow drip lines can be installed using small equipment or even hand labor to prevent disturbance to landscaping. The treatment system itself can be installed in virtually any accessible area.