On-site wastewater systems in South Australia are essential for homes being built beyond the mains sewer network. However, it also means taking responsibility for how wastewater will be collected, treated and managed on the property.
An on-site wastewater system is not something that should be selected after the house and landscaping have already been planned. The available space, number of occupants, soil conditions, site slope and local approval requirements can all influence which system is appropriate.
Understanding the main options early can make the planning and installation process considerably easier.
What Is an On-Site Wastewater System?
Every household produces wastewater from toilets, showers, sinks, kitchens and laundries. In a sewered area, this wastewater leaves the property through the public sewer network. Where no connection is available, it must be treated and disposed of safely on site.
According to SA Health, on-site systems use processes such as settling, biological treatment and disinfection to manage household wastewater.
The right system will depend on the property, how it will be used and the level of treatment required.
Option 1: A Conventional Septic Tank System
A septic tank provides primary treatment of household wastewater. Inside the tank, solids settle to the bottom, while oils and lighter material form a layer at the top. Naturally occurring bacteria help break down the waste.
The liquid effluent then leaves the tank and is directed to an approved land application or disposal area. The design of this area will depend on site conditions and local requirements.
Ri-Industries has manufactured concrete septic tanks in South Australia since 1947. Its engineer-designed tanks are manufactured from 40 MPa concrete and are available in several sizes to accommodate different property and household requirements. Internally sealed joints help reduce the risk of leakage, while child-proof and vandal-proof concrete lids provide additional security.
A conventional septic system may be suitable where:
- There is sufficient land for the required disposal area.
- The site’s soil and drainage conditions are appropriate.
- Reusing treated wastewater is not a priority.
- A straightforward, durable wastewater solution is required.
Septic systems still require responsible use, periodic inspections and pump-outs. The tank size, number of occupants and household water use will influence the maintenance schedule.
Option 2: A Secondary Wastewater Treatment System
A secondary treatment system takes the process further than a conventional septic tank. It uses additional biological treatment, filtration and, depending on the system, disinfection to produce treated wastewater that can be reused through an approved irrigation system.
This can be valuable on rural and semi-rural South Australian properties where homeowners want to make better use of available water. However, the treated water is not drinking water, and its reuse must comply with the approved system design and relevant requirements.
Ri-Industries’ Ri-Treat EP10 is a South Australian-manufactured secondary wastewater treatment system tested, certified and approved to AS/NZS 1546.3:2017. Its reinforced concrete construction, biofilter medium and bristle filters are designed to support reliable treatment and the reuse of household wastewater around the property.
Ri-Industries also supplies FujiClean wastewater treatment systems. Their compact fibreglass construction can offer an alternative where available space or site access makes installing a larger concrete system difficult.
A secondary treatment system may be worth considering where:
- Treated wastewater will be reused for garden irrigation.
- The site requires a higher level of treatment.
- Water conservation is an important consideration.
- Property conditions make a conventional septic arrangement less suitable.
Because these systems contain pumps and treatment components, they require regular servicing by an appropriately qualified technician to maintain performance.
Option 3: An Integrated Septic Tank and Pump Chamber
Some properties require a pump chamber to move effluent to the approved disposal area. A conventional arrangement may use a separate septic tank and pump chamber, requiring additional excavation and connections.
The Ri-Industries Ri-Scape combines the septic tank and pump chamber in one unit. This means only one excavation is required, potentially making it useful where space is limited.
Its integrated design can also reduce the number of underground connections. Ri-Industries recommends it for locations where land movement can create concerns around separate pump chambers, including some areas along the River Murray.
What Determines the Right System?
There is no single wastewater system that will suit every South Australian property. Before choosing one, several factors need to be considered.
Household size and water use
The number of bedrooms, expected occupants and daily wastewater volume will influence the required capacity. A system that is too small may become overloaded, while an unnecessarily large system could add expense without providing a meaningful benefit.
Soil and site conditions
Soil type affects how efficiently treated wastewater can be absorbed. Clay, sand, rock, groundwater levels and the slope of the land can all influence the design of the disposal or irrigation area.
Available space
The property must have enough suitable land for the system itself and its approved land application area. Required setbacks from buildings, boundaries, water sources and other site features must also be considered.
Access for installation and maintenance
The tank must be delivered and placed safely, and maintenance providers will need ongoing access for inspections, servicing or pump-outs. It is important to consider access before buildings, fences and landscaping restrict the site.
Future plans
A household may grow, a home may be extended or a property’s use may change. Planning for foreseeable changes can help avoid having to replace or substantially modify the wastewater system later.
Approval Comes Before Installation
In South Australia, approval must be obtained from the relevant authority before an on-site wastewater system is installed or altered. Depending on the nature and location of the development, this will generally involve the local council or SA Health.
The application may require site and soil assessments, system specifications, building plans and details of the proposed wastewater disposal or irrigation area. The wastewater product itself must also hold the appropriate South Australian approval.
Speaking with the local council, wastewater professional, builder or plumber early in the design process can help identify the requirements that apply to a particular site.
Plan the Wastewater System Early
A well-designed on-site wastewater system should operate quietly in the background for many years. Achieving that begins with selecting a system that suits the household, the property and South Australian requirements.
Ri-Industries manufactures and supplies a range of wastewater solutions, including concrete septic tanks, the Ri-Scape integrated system, the Ri-Treat EP10 and FujiClean treatment systems. With nearly 80 years of South Australian manufacturing experience, our team can work with homeowners, builders and plumbers to help identify an appropriate solution for the project.
If you are building or renovating beyond the sewer network, contact Ri-Industries on 08 8444 8100 or request a quote to discuss your site and wastewater requirements.