Septic Systems
Types of Septic Systems
There are many types of septic systems in use today, and the best choice can vary based on a variety of factors. From household size to local laws and regulations, it’s essential to consider all aspects before deciding on the ideal system for your needs.
Common types of conventional and alternative septic systems include gravity fed, mound, pressure dosed, sand mound, treatment plant systems, at-grade absorption systems, drip distribution systems, evapotranspiration systems, aerated gravel filter systems, multiple tank configurations, and more.
For a better understanding of these options and their specific feature and benefit details, look for detailed fact sheets that provide further information.
Conventional Systems:
Septic Tank
Septic tanks are an important part of wastewater management, as they receive and partially treat raw domestic sanitary wastewater. They typically consist of a buried, watertight tank that allows wastewater to enter and settle within it. The solids sink to the bottom, while greases and lighter solids float to the top; these solids stay in the tank, while the wastewater is discharged from it for further treatment and dispersal.
Conventional System
A conventional wastewater treatment system refers to a decentralized, on-site treatment system that has been around for many years. This type of system typically consists of a septic tank and a subsurface drainfield made of either trenches or gravel or stone beds. In this design, the effluent from the septic tank is piped into an underground trench filled with stone or gravel, on top of which geofabric material is placed to stop contaminants from entering.
As effluent filters through the stone, it is further treated by soil microbes below the gravel or stone trench. Keep in mind, however, that these kinds of systems are quite large in terms of their overall footprint and may not be suitable for all residential sites or conditions.
Chamber System
The Chamber System is an alternative to the traditional gravel or stone drainfield system and has been in use for over 30 years across multiple states. This system comprises interconnected chambers with soil in the area surrounding and above them. The pipes carrying wastewater from the septic tank run through these chambers, which come into contact with the soil. This is where microorganisms break down the effluent, thereby treating it.
Such systems are manufactured using recycled materials, making them highly eco-friendly as well as cost-effective. In addition, they offer greater ease of delivery and construction compared to their predecessors, as well as a viable solution for vacation or seasonal homes, regions sparsely populated with gravel, or areas that are abundant in plastic chambers.
Alternative Systems:
Drip Distribution System
Drip distribution systems are an effective way to disperse effluent into a wide variety of drainfields. Because the drip laterals are installed within the top 6 to 12 inches of soil, there is no need for a large mound of soil. While this system is cost-efficient and low-maintenance, it does require additional components such as electrical power and a large dose tank after the septic tank for timed delivery of wastewater to the drip absorption area.
Aerobic Treatment Units (ATUs)
Aerobic Treatment Units (ATUs) are small sewage treatment systems that use many of the same processes as a municipal sewage plant. The system uses oxygen to stimulate bacterial activity, which helps break down pollutants in wastewater effluent.
Depending on the circumstances, an ATU may have a pretreatment tank and a final treatment tank, including disinfection, to further reduce pathogen levels. ATUs work well for homes on smaller lots, in inadequate soil, or too close to a surface water body sensitive to contamination by nutrients. Regular maintenance will be required for any ATU installation.
Mound Systems
Mound systems are an effective choice for areas that have shallow soil, high groundwater levels, or shallow bedrock. They involve setting up a sand mound with a built-in trench drainfield that houses the septic tank’s effluent. The effluent is then pumped in prescribed doses and naturally dispersed into the native soil as it passes through the sand and gets treated along the way. Although mound systems can be very helpful for certain environmental conditions, they do require a lot of space and regular upkeep to function properly.
Recirculating Sand Filter System
A recirculating sand filter system is an advanced method of wastewater treatment. It utilizes a pump chamber, a sand-filled chamber, and a drainfield to facilitate the process. Effluent flows from the septic tank to the pump chamber, where it is then pumped to the sand filter. This sand filter may be composed of either PVC-lined material or concrete, and it is filled with a sand medium that filters and treats effluent as it moves through its pipes at low pressure.
Once treated, the further clarified wastewater can be discharged into the drainfield area. This type of wastewater treatment is especially ideal for sites with high water tables or those close to water bodies due to its high level of nutrient treatment capabilities; however, they tend to cost more than standard septic systems. Effluent flows from the septic tank to a pump chamber. It is then pumped to the sand filter and treated as it filters through the sand.
Evapotranspiration System
Evapotranspiration systems are designed to be used in specific climate conditions, ideally on arid turf with ample heat and sunlight. Unlike other types of septic systems, the drainfield is lined with a watertight material like plastic or fiberglass to hold effluent, which then evaporates into