What is a septic tank?

Septictank 3D

A septic tank is used for collecting and treating wastewater on a property that is not connected to the main sewer system.

They are installed underground, and make use of natural processes to treat the sewage they collect. Typically made up of two chambers or compartments, septic tanks receive wastewater from an inlet pipe.

The wastewater enters the first chamber and separates over time, with solids settling at the bottom, oils and greases forming a layer of scum at the top, and a layer of relatively clear water remaining in the middle.

The clarified wastewater is then removed from the second chamber via an outlet pipe, which transports the water into the septic drain field, also known as a seepage field or leach field. The remaining scum and solids in the tank are broken down by naturally occurring bacteria and what is left is pumped periodically.

Septictank 3D

Septic tank maintenance advice

Even though septic systems require relatively little maintenance, certain considerations need to be kept in mind by septic tank owners.

For example, the following items should never be flushed down the drain or toilet:

  • Food waste
  • Fat, oil and grease
  • Plastic bags
  • Nappies
  • Sanitary towels, including tampons, applicators and wrappers
  • Cotton buds
  • Condoms
  • Bandages and plasters
  • Baby wipes
  • Medicines, needles and syringes*
  • Cleaning wipes
  • Razor blades

Not only can these items block the inlet and outlet pipes, they can also disrupt the biological separation process taking place within the tank itself.

Septic drain field treatment

Septic drain or leach fields do not usually require a lot of maintenance, but there are certain things septic tank owners should do to make sure it remains well protected and operational. They include:

  • Avoiding planting trees or plants on the area, as their roots can damage the underground pipes
  • Avoiding driving over the field
  • Avoiding covering the field in concrete

Emptying septic tanks

The sludge that remains at the bottom of the tank following the natural biological separation process must be periodically removed from the tank by a vacuum truck, to avoid it overflowing into the leach field.

How often this happens depends on a range of factors, from the size of the tank, the amount of waste that is added to the tank, and a host of other variables. Some need emptying every couple of years, while others can go for decades before needing to be emptied.