Primary or Secondary Waste Treatment Systems: Which is Right for You?

The variety of wastewater treatment systems at your fingertips may feel slightly daunting. Not only are there different types of septic systems, but there are many different manufacturers in marketplace as well. Fortunately, deciding between one and the other is fairly simple, and we here at SSA will happily help you out if you find yourself stuck in the mud.

To start, here we’re going to talk about the differences between these two kinds of systems, and which one is right for you. depending on the location, and type of land you’re installing it on.

Primary Waste Treatment Systems

When we talk about a “primary” system, what we really mean is a conventional septic tank with an absorption trench and no other supplementary systems. The effluent flows from the Septic Tank to the trenches via gravity (or in some cases it is pumped). The effluent is distributed along the length of the trench through pipes with holes in them. Trenches are filled with gravel and sand, which helps to filter out the pathogens, toxins and other contaminants before it disperses through the soil. Vegetation (typically grass) is planted on top of trenches to allow the take up of nutrients and to help remove excess water through evapotranspiration. Absorption trenches are excavated underground so that the effluent doesn’t come into contact with humans and animals because the quality of the effluent is generally poor.

Generally, primary waste treatment systems are not allowed to be used on blocks smaller than two acres, or in environmentally sensitive areas (ie near waterways that lead to potable drinking reserves) and they are not allowed on commercial premises due to the poor quality of the final effluent. And sadly, you won’t be able to use the effluent to water your gardens and lawns.

However, these systems are very cost-effective to install and offers incredibly low maintenance. And, if your land has a significant slope to it, you may be able to install the septic tank and trenches without an electrical pump, which can save you a lot on power. This is why many landowners choose to go with a simple primary system – it’s cheaper, it’s easy to look after, and you don’t have to worry about it for years at a time.

Secondary Waste Treatment Systems

Secondary systems like Aerated Wastewater Treatment Systems (AWTS) and sand filter septic systems are supplementary to the primary treatment system. They treat the waste to a much higher quality, allowing it to be used to maintain a garden on your property and contribute water back to the earth. Many people have these installed because they are environmentally beneficial, and they also reduce the risk of contamination on your land and of local waterways.

Sand Filter Septic System

Much like a primary system, this kind of system should only be used on larger sites because you need more room to fit in all the components: a Septic Tank, a Sand Filter, a Pumpwell or Final Chamber and either absorption trenches or subsurface irrigation. However, the final quality of the effluent is excellent in comparison. One of the biggest benefits is that you are able to hook up your Sand Filter to either subsurface irrigation, so you can use the processed wastewater to feed your plants. Keep in mind that these plants should never be anything that you or any livestock will eat, as the possibility of contamination is still too high when ingesting the plant matter.

If you choose this kind of system, be prepared to shell out a few more dollars during the installation, as well as in the event of a malfunction. And keep in mind that these systems really don’t like rocky, sandy or steep sites or properties in high water table areas. But if none of this applies to you, these systems are low maintenance and great for the local environment.

Aerated Wastewater Treatment System (AWTS)

An Aerated Wastewater Treatment System (AWTS) is the most versatile installation type as it can be used on all types of properties, including steep, rocky or sandy, or sites with limited space or high water table areas, and even commercial premises. With regular maintenance and care, these systems will last a long while, and you’re able to use the final effluent to water your inedible plants.

Keep in mind that you have to have the system serviced quarterly, as it is mechanical and therefore has a lot of moving parts. They also require a continuous power supply. However, for the versatility they offer, it’s unsurprising that many landowners opt for an AWTS.

 There are many different brands of AWTS available on the market, which can lead to a lot of confusion. But you can have peace of mind that any system that has tested against the Australian Standards and has a current Certificate of Approval issued by the Environment Protection Authority (EPA) of Victoria, then it will be good as gold. Septic Systems Australia has installed many different types of systems over the years and we have our favourites! So call us if you would like some advice on which system to choose.


Make the right choice.

We’re passionate about septic systems, and we love to help Australian landowners decide on which kind of system they want to go for. If you’re in the market for a wastewater treatment system, talk to the people here at Septic Systems Australia!