Conventional Septic System
A conventional septic system uses gravity to move household sewage into the septic tank. Sewage is separated into layers, with solid waste settling at the bottom and liquid sewage rising to the top.
When liquid sewage rises to the level of the outflow pipe, the liquid waste flows into the drain field where it decomposes further. The drain (or leach) field is the permeable soil surrounding the tank that absorbs and naturally treats liquid residue. This prevents the contamination of contaminate runoff water or leaks into the water table.
Conventional septic systems are usually the most affordable, costing around $2,000–$7,000.
Anaerobic Septic System
The anaerobic septic system uses anaerobic bacteria to break down waste in the septic tank. These systems don’t require additional chemicals or power and are an affordable option for homeowners.
However, anaerobic systems don’t clean the tank and require a larger drain field to work correctly. If you have the space to accommodate a large drain field, an anaerobic system could be a viable option for your property. Additional costs for installing the installation or a drain field will also add to the final price of this installation. These systems will cost $3,000–$8,000 on average. The added size increases the average cost to $3,000 to $8,000.
Alternative Septic System
An alternative septic system collects sewage the same way as a conventional system, but it breaks down the tank’s sewage using oxygen instead of naturally occurring bacteria. Homeowners with limited yard space or looking for more compact options should consider alternative septic systems. These systems are also used with a high water table, poor soil, or high bedrock.
Drain fields for alternative systems generally need less land and release cleaner wastewater. This benefit comes at an increased cost, with systems usually priced around $4,000–$15,000.
The following types of alternative septic systems are available for homeowners:
- Chambered septic system: Replacing the need for a gravel/stone system, chambered systems use gravelless drain fields with leaching chambers for filtration. They are ideal in areas with high groundwater tables or limited gravel. The gravelless chamber septic system typically costs $4,000–$10,000.
- Constructed wetland septic system: Similar to the natural process in real wetlands, this system cleanses wastewater using bacteria, microbes, and plants. The waste then helps those plants to thrive. This design is the most eco-friendly septic system available. You should budget between $7,500 and $15,000 for this septic system type.
- Drip distribution septic system: Drip systems are made to “irrigate” septic water over a larger area using long tubing throughout the leach field. Homeowners will need ample space and power for this type of system. These systems range between $4,000 and $10,000 on average.
- Evapotranspiration septic system: These systems use a large open-air tank to allow the effluent, or liquid waste, to evaporate naturally. This type of system works best in climates that receive abundant sunlight and heat. Evapotranspiration septic systems cost $10,000–$15,000.
- Pressurized distribution septic system: This system uses pressure to distribute effluent evenly. It can be paired with other septic systems that focus on water treatment. The pressurized septic system, which works well with a high water table, costs about $6,500–$9,000.
Engineered Septic System
Engineered septic systems are the most complex. They are generally needed due to poor soil or because the home resides on an uphill slope. Similar to alternative and conventional septic systems, engineered systems collect and separate waste in a tank. Instead of relying on gravity to drain, the liquid waste needs to be pumped into the leach field to distribute throughout the land evenly.
These systems have the highest price tag because they require more moving parts and specialty equipment. These systems generally cost $7,000–$20,000.
Below are some examples of engineered septic systems:
- Mound septic system: Mound systems use mounds of sand to clean wastewater instead of a typical leaching field. These systems require the installation of sand and a pump tank, which increases the installation cost from $10,000–$20,000.
- Aerobic system: By pumping oxygen into the treatment tank, these systems generate naturally occurring bacteria to process the waste. If you prefer an aerobic septic system, you can expect to pay around $11,000–$19,000.
- Recirculating sand filter system: This septic system uses sand to filter effluent out after leaving the pump tank. The treated water then flows to the drain field. Sand filter septic systems work best in areas near bodies of water or with a high water table. You should budget $6,000–$10,000 for your project.