What is a septic tank and how does it work?

What is a Septic Tank?

Septic tank is an underground tank where all the waste discharge accumulates. It is used for waste water treatment through the process of biological decomposition and drainage. A septic tank uses natural proven or advanced technologies to treat wastewater materials discharging from the household plumbing produced by washrooms, kitchen drains and laundry. Septic tank designs are usually made of simple design usually rectangular or round in shape. It is made up of fiber glass, plastic or concrete.


How Does It Work?

Septic tanks work by collecting the water waste and human excreta in a large underground tank, basically this is how it is used in rural areas. Septic tanks are usually underground, and should be 15 feet away from any home. It may be comprised of two compartments, in the 1st compartment it receives waste water from inlet pipes, and effluent discharge is from the 2nd compartment.

Septic tank requires regular maintenance and some common precautions should be taken when it is handled. Property owners should plan a proper residential septic system design to avoid spreading bacteria, virus causing infection. Septic site plan should be made in such a way that the septic tank does not create any harm to the natural environment. If the septic tank is not pumped periodically then the effluent retention time is dramatically reduced allowing solids to exit to the field causing field failure and allowing the sewage can flow into the ground surface and create a backup in sinks and washrooms. In a septic tank all the organic materials will settle at the bottom and soap will float to the top.  The effluent being treated is between these top and bottom layers, as the distance between these layers gets closer that is what fills the tank.


What is a septic tank and how does it work


The septic tank has two  pipes (typically) one for inlet and the other for outlet. The inlet pipe is used in the septic tank to move the water waste from the household, and it gets collected in the septic tank. The wastes are kept for long enough inside the septic tank, so that solid and liquid wastes separate it from each other. The second pipe is the outlet pipe or the drain pipe. This outlet pipe separates out the preprocessed waste water from the septic tank and spreads it evenly in the leach field. When the waste water is collected and settled in the septic tank, it divides itself into three layers. The first layer is oil or grease which floats on top of the waste, and this is termed as ‘scum’. The second layer contains the waste water and the waste material referred to as effluent.


What is a septic tank and how does it work –


The third or the last layer contains the particles which are heavier than water and forms sludge. Bacteria present inside the tank helps in breaking down the solid waste particles, which then makes it easy for the liquid to separate and drain away easily.  As a part of maintenance, the materials which are settled at the bottom of the septic tank need to be removed.  Detailed steps of how a septic tank works are listed below:

  1. Water waste from the household runs through one main pipe leading to the septic tank.
  2. Underground septic tank holds the liquid waste. It needs to hold the liquid waste long enough so that the solid particles settle at the bottom and oil and grease separates itself on the top.
  3. After the process the effluent will be able to exit the tank into the drain field.
  4. The waste water is then discharged in the porous surfaces of the drainfield.
  5. The soil then accepts, treats, and disperses waste water as it percolates through the soil, ultimately discharging to the groundwater.