Managing Wastewater

Management of wastewater is a key consideration for any land development or new build. Depending on where your land is located in relation to Council pipes and sewerage, you may need to install your own septic system if connecting to a waste management facility is not possible.

What does a Septic tank do?

A septic tank is used to provide the primary treatment of wastewater from a dwelling and is often combined with other treatment measures. Primary treatment involves sedimentation, flotation, clarification and anaerobic digestion. Thus, Septic tanks are responsible for separation of human waste from grey water. Almost the same process as a ‘garden compost’.

Septic tanks come in all shapes and sizes, and must be designed according to AS/NZS 1546.1:2008 On-site Domestic Wastewater Treatment Units Septic Tanks. If you’re located in NSW, septic tanks may require accreditation by NSW Health, be baffled and include an outlet filter dependent on size and capacity.

How does it work?

All grey waste produced will be deposited into the septic tank for primary treatment which includes break-down of the heavier waste and bacteria to allow water to flow into the next stage. The by-product (Sludge) will fall to the bottom of the tank will have to be pumped out by a certified tradesperson as a scheduled maintenance requirement every three to five years. Flotation residues (for instance, grease, oil and other low density materials), rise to the surface of the tank and form a scum layer which helps create an anaerobic environment for organic solids to breakdown. The clarification settled wastewater remains in the middle of the tank and is drawn out for further treatment/disposal.

It is important to choose the correct size septic tank for the right application.  For example, households of four people would require a mid-range septic tank of about 3000L. Commercial applications may need a bigger tank where there are than 7 people to cope with the amount of inflow.   

In determining the best size for your situation, a good first step is to talk to your local council about the tank size that is required. Considerations like intended volume/traffic and whether it be residential, recreational, or commercial will help determine size required.  Generally, tanks range from about 2000-4000L in capacity. Once you have selected your septic tank size, the second important factor is placement of your septic tank. Given septic tanks aren’t 100% sterile even at the end of the process, there is an extensive list of NSW Health Regulations to be mindful of to ensure your septic will not impact the surrounding environment i.e., neighbouring houses, streams and bore water systems. 

Does your Septic tank meet the Australian standard and how long will it last?

The current Australian standard for septic tanks is AS/NZ1546.1 which can be found on the manufacturer’s website or on the physical product.

While there are many types of septic tanks on the market such as plastic, steel and concrete and you may be wondering which option to choose. Consider these two things, the materials to manufacture steel and plastic tanks may be subject to deterioration much quicker than a concrete tank. which in turn may increase maintenance schedules and or even replacement. Refer to our TCO blog for more information on “Total Cost of Ownership”. Second thing to consider is the features and benefits of a concrete tank. Concrete products are rated highly for compressive strength and durability. For instance, At Mid West Concrete all our septic tanks are not only produced in strict accordance with the current Australian Standard but are also rigorously tested to ensure compliance, quality and performance.

If you’d like more information on precast concrete septic tanks, contact the friendly Mid West Concrete team.