We realise that having a septic tank and maintaining it correctly is of vital importance. However, many of us are baffled or clueless as to how a septic tank actually works. We know that it works, as we do not experience issues with sewerage or blockage of toilets or drains. But what exactly is involved with ensuring its positive actions? How exactly does that big tank that is buried in your yard work?

Firstly, there are three main “parts” of your septic tank system – the tank itself, the soil and the drain/leach field. The wastewater is first transported through your pipelines to the septic tank. It then stays there for a retention period of about 24 hours. During this period, the solids separate from the liquids. The solids sink to the bottom of the tank as sludge while the liquids or lighter waster rise to the top. The lighter waste forms a scum layer at the top of the tank. The wastewater then flows into a second compartment of the tank. A tank component known as a “tee” ensures that it flows slowly and steadily so as not to disturb the sludge below and encourage sludge particles into the water. After the retention period, the wastewater, which is now relatively free of solid waste, flows into the drain or leach field. Pressure is what usually causes the liquid wastewater to flow out of the tank. The sludge however, remains in the tank. It is for this reason that the tank must be pumped every three years or so as the sludge can otherwise build up and cause a blockage.

The leach field is where the wastewater gets initially treated. This section of the system is made up of perforated pipes. The treated liquid wastewater (also known as effluent) flows out of the pipes and through a gravel layer before finally reaching the soil. Some septic tank systems may include a distribution box which catches the wastewater from the pipes and disperses it correctly throughout the soil.

The soil is the final stage of treatment for the waste, the organisms in the soil treat the waste. It is then percolated down and eventually out of the soil. Eventually, it ends up joining up with water on the surface. The reason why soil testing is of key importance before installing your septic tank is because it has such an important role to play in the process. The ideal type of soil is dry and permeable. It should not be too coarse or too tight, as soil in this state will undoubtedly cause unwanted problems in the future.

It is a pretty straight forward process but yet such an effective one. For it to work however, the planning stage is of key importance. The tank must be positioned correctly, the surrounding drainage field must be fit for purpose and the soil must be of a correct quality and standard.