Types of Septic Tank Systems
A septic tank system is an underground network of pipes carrying effluent (liquid waste and sewerage) from a household to designated treatment areas using tanks, chambers, pits, trenches or mulched areas to dispose of all wastewater from a household.
Septic tank systems are used in areas where reticulated sewerage is not available.
A septic tank system generally has three main components to it:
1. Effluent detaining and settling stage
This occurs in a septic tank and is known as primary treatment. The septic tank must be capable of slowing the flow of approximately 1000 litres per day that leaves a typical household.
2. Effluent treatment stage
Known as secondary treatment, this stage includes the use of sand filters, treatment plants and effluent disposal trenches.
3. Effluent disposal stage
This stage must be capable of containing the 1000 litres per day of treated effluent on the property. Examples include effluent disposal trenches, subsurface irrigation systems, and surface irrigation systems.
There are two main type of septic tank systems (wastewater treatment systems):
- a standard septic system
- a treatment plant
Both are used for the treatment of wastewater generated by toilets, kitchens, bathrooms and laundries from your household. Treatment plants generally produce a cleaner, low odour effluent.
When your household wastewater flows into the wastewater tank most of the solids in it sink to the bottom. Over time, microorganisms will decompose these solids into sludge and gasses. The sludge builds up on the bottom of the tank while the gasses and other lighter materials rise to the top of the tank and form a floating layer of scum. The wastewater left in the middle is released to a disposal field set aside on your property.
All effluent must be disposed via sub-surface irrigation and, if from a treatment plant, the effluent must be evenly distributed via pressure compensated piping.