Septic System Basics - How Septic Systems Work
Septic systems are expensive pieces of equipment. In fact, for the majority of households, it will be the most expensive household fixture. Over 20% of US households rely on an onsite septic system to treat wastewater, solids and grey water from the house.
On this page you will find information on how septic systems work, the different types of septic systems, how to maintain a system, danger signs and frequently asked questions.
Types of septic systems
Some of the most common types of setups are:
Aerobic Treatment Unit (aerobic systems)
What is a septic system?
There are two main components that make up septic systems, they are the septic tank and a leach field.
What is a septic tank?
For full detail on what a septic tank is, see the septic tank page for full information.
What is a leach field?
For more information on what a leach field or absorption field is see the leach field page for further information.
How do septic systems work?
All liquid effluent, human sewage and wastewater flows through the household plumbing system, out of the home via the main drain drainage pipe and the effluent enters into the septic tank via the inlet pipe.
The job of the septic tank is to partially decompose lighter solids and do the majority of the processing and effective treatment of the wastewater. This job is completed when the lighter solids (sludge) and heavy solids settle on the bottom and the scum accumulate into a scum layer (including grease and oils) forms at the top leaving a layer of water in the middle.
The semi treated liquid wastewater or effluent then leaves the tank via the outlet pipe which often has effluent filters fitted to ensure sludge and sewage remain in the system and only septic tank effluent flows via the distribution box into the soil absorption field.
The absorption field is an allocated area in the back yard where small perforated pipes enable the liquid wastewater to be distributed into the surrounding soil to naturally remove pathogens including coliform bacteria and the soil treat any further nasties. Once the surface water has dissipated it will naturally make its way to the groundwater under the earth.
That is how septic systems work, if you have any further questions on how septic systems work, see the frequently asked questions below.
Frequently Asked Questions
How long a system lasts will depend on how well you treat your conventional septic system. To avoid property damage to your septic tank you should avoid driving over the ground surface over the septic tank, distribution box and absorption field with heavy vehicles.
There is a range of septic tank additives on the market for a conventional system to address excess sludge and scum. These range from old wives tales to treatments designed and developed by some of the top colleges in the US. It is important to note that using a septic treatment does not mean you can abuse your septic tank, care when using things like garbage disposals and what you put down your toilet and sink is very important for your system.
Periodic septic system maintenance will prevent a large repair or maintenance bill from a septic professional in the future. This can be as simple as not putting any household chemicals, antibacterial soaps, cigarette butts, motor oil, paper towels down toilets or using garbage disposal liberally.
Using less household wastewater is always a plus whether you are using a well or you are connected to county water. If you put too much liquid into your system at one time, for example, you do back to back loads of washing, you can flush out the natural bacteria in your tank and the soil absorption field can not handle a large amount of water and this can lead to groundwater around your tank or an overflowing system.