Septic tanks are a key part of on-site waste treatment systems. The tank is a watertight container that receives waste from the home and stores it while it decomposes. Bacteria in the tank break down the waste, which is then released into the soil through a leaching field.
There are a variety of septic tank systems on the market, but all of them use one of three basic types of technology: gravity tanks, pressure tanks, or membrane tanks. Gravity tanks rely on the weight of the water to push the waste through the tank and into the soil. Pressure tanks use a pump to push the water and waste through the tank and into the soil. Membrane tanks use a special membrane to separate the water from the waste, which is then released into the soil.
The type of septic tank system you need depends on the size of your home, the slope of your land, and the type of soil you have. Your local health department can help you choose the right system for your home.
Types Of Septic Tanks
Septic tank systems come in a variety of sizes, and each one has its own strengths and weaknesses. Here are some of the most common types of septic tanks on the market today:
Conventional Septic Tanks
Conventional septic tanks are the most common type of septic tanks around. It uses gravity to move the waste from the house through the tank and into the soil. Conventional septic tanks consist of 2 chambers. The first chamber solids settle, fats, oils, and grease float, and microbes slowly break down the waste.
In the second chamber, further settlement takes place. In there the effluent liquid is then discharged through perforated pipes into a designated yard or leach field. This process is however usually an undesired outcome for homeowners who are usually not too satisfied with the bog patch this system creates.
Conventional septic tank site suitability:
| Land Size Requirement | Not allowed on blocks smaller than 8000m2 |
| Quality Of Final Effluent | Poor quality |
| Suitable For Environmentally Sensitive Areas | No |
| Suitable For Sandy Sites | Yes |
| Suitable For Rock Sites | Yes |
| Suitable For Steep Sites | Needs a site inspection |
| Suitable For High Water Table Areas | No |
| Suitable for Subsurface or Surface Drip Irrigation | No |
| Can Be Used On Commercial Premises | No |
| Maintenance Requirements | Desludged every 3-5 years |
Aerobic Septic Tanks
Aerobic septic tanks are a type of tank that uses a pump to move the waste through the tank and into the soil. If you have a home that has limited space then this type of tank could be a good choice. An aerobic septic tank is much like a wastewater treatment plant but on a smaller scale.
Simply put, this system works by breaking down the solid components, then works on stripping the nitrates and phosphates. From there it will sanitize the water so it is safe to use for garden irrigation. See below the setup of the fujiClean CE-1500EX system.
| Land Size Requirement | No minimum requirement |
| Quality Of Final Effluent | High Quality |
| Suitable For Environmentally Sensitive Areas | Yes |
| Suitable For Sandy Sites | Yes |
| Suitable For Rock Sites | Yes |
| Suitable For Steep Sites | Needs a site inspection |
| Suitable For High Water Table Areas | Yes |
| Suitable for Subsurface or Surface Drip Irrigation | Yes |
| Can Be Used On Commercial Premises | Yes |
| Maintenance Requirements | Yearly service and pumped out every 3-5 years |
Aerated Septic Tanks
An aerated septic tank is fast becoming the popular septic tank being installed around Australia. The treated wastewater from this tank is classed to a high standard that can be used for irrigating gardens around your home. Although, the usual aerated septic tank system is more complicated than others and needs several pumps for it to function. This means it requires a more frequent maintenance routine.
An aerated septic tank consists of 3 chambers. The first chamber is used for the solids to settle to the bottom and allow the scum to float to the top. The second chamber makes use of air to further assist bacteria in breaking down the solids. The third chamber allows for further settling of solids with a final compartment that uses chlorination to disinfect the wastewater before pumping it out of the system. The wastewater pumped out can be used for subsurface and surface drip irrigation. However, the chlorine found in it means it is not the most ideal use case for garden irrigation. See the image below of an aerated system setup:
| Land Size Requirement | No minimum |
| Quality Of Final Effluent | High quality |
| Suitable For Environmentally Sensitive Areas | Yes |
| Suitable For Sandy Sites | Yes |
| Suitable For Rock Sites | Yes |
| Suitable For Steep Sites | Yes |
| Suitable For High Water Table Areas | No, needs site inspection |
| Suitable for Subsurface or Surface Drip Irrigation | Yes |
| Can Be Used On Commercial Premises | Yes, depending on the size of the premise |
| Maintenance Requirements | Serviced every 3 months & Desludged every 3-5 years |
How Much Does A Septic Tank System Cost
In Australia, there is a wide range of different septic tank systems available on the market. All come with their different pros and cons as well as different cost ranges and ongoing maintenance costs. There is plenty to consider when looking to buy a septic tank system for your home. Take a peek at the resource links below to continue your research before you make your decision!
So how much should you expect to pay for a septic tank system in 2022?
| System Type | Installation Cost | Maintenance & Ongoing Costs |
| Sand Filter Septic Tank System | $15,000 – $20,000 | $150 pa & &300 every 3-5 years |
| Aerobic Spetic Tank System | $10,000 – $20,000 | $300 pa |
| Aerated Septic Tank System AWTS | $10,000 – $20,000 | $300 pa & $900 every 5+ years |
| Conventional Septic Tank | $4,000 – $12,000 | $300 every 3-5 years |