Septic Tanks and Systems

Septic tanks have been used in un-sewered areas for many years as the most suitable form of primary treatment of sewage and are the only option available to homes in the rural areas of the Edward River region, including Blighty, Conargo, Pretty Pine and Wanganella.

The septic tank is an underground watertight tank generally constructed of concrete or plastic which is usually divided into at least two compartments. The tank receives all sewage and separates the solid portion of the waste from the liquid portion. The liquid portion (effluent) passes out of the tank after approximately 24 hours. The tank performs three functions:

• it acts as a settlement chamber for solid materials
• it allows some bacterial breakdown of waste materials to occur
• it acts as a storage chamber for undigested solid materials which must be removed periodically (usually every 4 years).

There are several methods of disposing of the effluent after it has passed through the septic tank. One method is subsurface soakage, known as Absorption Trenches. With this type of system, the effluent is distributed to the base and sides of the trench over its entire length for absorption and final biological treatment by the soil. These trenches work best in light sandy country where there is a good absorption rate.