What is a septic tank?

Septictank 3D

A septic tank collects and treats wastewater at a property that is not connected to the mains sewer system.

Installed underground, a septic tank makes use of natural processes to treat the sewage it stores. Usually made up of two chambers or compartments, the tank receives wastewater from an inlet pipe.

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.

This clarified wastewater enters the second chamber. It then exits via an outlet pipe into a 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 should be professionally removed periodically.

Septictank 3D

Septic tank maintenance advice

Septic systems require relatively little maintenance, but septic tank owners need to observe certain rules to make sure the tank system operates effectively.

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

These items will block the inlet and outlet pipes, and also disrupt the biological separation process taking place within the tank itself.

Septic drain field treatment

Similarly, a few simple rules will keep septic drain or leach fields healthy:

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

Emptying septic tanks

The sludge that remains at the bottom of the tank after the natural biological separation process has ocurred, must be removed from the tank by a vacuum truck. This stops it from overflowing into the leach field.

How often it needs emptying depends on a range of factors, from the size of the tank to the amount of waste that is added to the tank, and other variables. Some need emptying every couple of years, while others can go for decades before needing to be emptied. Your local specialist will help you plan this service.