Your Questions On Waste Water Answered...


On many rural and semi-rural building sites reticulated sewer, or ‘mains sewer’ is not available, and the only option is to install an onsite wastewater system. This is a system designed to process the wastewater (sewage) from your home and dispose of it safely on your site.

An onsite wastewater system must be designed by an accredited designer, approved by your local council, and installed by a licensed plumber. However, it is good to be familiar with the options available so that you can discuss them with your builder, plumber or wastewater system designer

What are the options for on-site wastewater systems?

The basic option for disposing of your wastewater onsite is a septic system. Wastewater is piped into a large storage tank, where the waste is broken down through a natural process, and the liquid waste flows out the other side of the tank into underground absorption beds. Solid waste falls to the bottom of the tank and may occasionally require pumping out

If your site is not suitable for the basic septic method, there are several other options…

There are several advanced septic systems available that work on a similar principle to the basic septic but have engineered absorption areas to ensure the septic can safely dispose of the liquid waste. This may mean having raised beds of imported material such as sand or mulch in which the liquid waste can be absorbed, or having a gridwork of small pipes with dripper holes, again to assist with disposing of the liquid waste. Examples of advanced septic systems that we use here at Tasbuilt include the AES ( or Eljin ( systems

What is the difference between a septic and AWTS?

AWTS (Aerated Wastewater Treatment Systems) have multiple compartments or ‘chambers’ in the tank. In the second compartment, air is mixed with wastewater to assist bacteria to break down the solids. This produces a much cleaner effluent that can be disposed of through either subsurface lawn irrigation or through dripper lines in raised mulch beds.

What are the costs of a septic vs AWTS

A basic septic is generally the cheapest option, with minimal ongoing costs. A basic septic system supplied and installed, including the connections around your home, will be around $12,500.

An advanced septic is a dearer option but generally also has minimal ongoing operating costs. Depending on the design an advanced septic could cost a total of $15,000-$25,000.

An AWTS has varying install costs depending on the system design (generally around $15,000-$20,000) but also attract an ongoing maintenance cost which varies depending on the chosen supplier. At Tasbuilt we use a range of AWTS including Fujiclean ( )

Why might my property not be suitable for a basic septic?

There are many reasons your wastewater designer may not be able to specify a basic septic system for your property. Some of these factors are;

  • Proximity to water courses, dams or rivers
  • Not enough slope
  • Not enough land area


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