Septic tanks and sewage treatment

Septic tanks treat sewage at the place where it is located, rather than transporting the waste through a treatment plant or sewage system. Septic tanks are usually used to treat sewage from an individual building.

  • Untreated sewage from a property flows into the septic tank and the solids are separated from the liquid.
  • Solid material is separated depending on their density. Heavier particles settle at the bottom of the tank whereas lighter particles, such as soap scum, will form a layer at the top of the tank.
  • Biological processes are used to help degrade the solid materials.
  • The liquid then flows out of the tank into a land drainage system and the remaining solids are filtered out.