What is a Septic Tank?

Septic Tanks are the ideal, economical and trouble free sewage bio-digesters. It is believed the septic tank system was first introduced to South Africa by the British military in 1898. The term “septic” refers to the anaerobic bacterial environment that develops in the tank and which decomposes the waste discharge into the tank. A septic tank is basically a vessel buried underground, the purpose of which is the collection, storage, and to some limited extent, treatment of sewage. A typical septic tank system normally operates by gravity, and consists of a tank and a soakaway drain. Untreated waste water from a property flows into the septic tank, where the solids separate from the liquids. Some solids, such as soap scum or fat, will float to the top of the tank to form the scum layer. Heavier solids settle to the bottom of the tank as sludge. Self forming bacteria in the tank help the system digest these solids or sludge where a natural process of anaerobic decomposition occurs in the tank which reduces the amount of solid matter and provides some treatment of the waste. The remaining liquids flow out of the tank to a soakaway and eventually get taken up through the root system of plants or added to the groundwater. Baffles built into the tank hold back the floating scum from moving past the outlet of the tank.


Septic tank care is crucial to maintain a healthy septic system. Although the septic system is quite self sufficient, there are things you can do to help the system work efficiently. Microbes in your septic system will naturally break down the organic material that drains into your septic tank. The broken down material will naturally drain out of the septic tank and into the soakaway. There are some solids that cannot drain out of the septic tank and this is normal. Regular septic tank care requires you to desludge these solids every 3 – 5 years. The size of your septic tank, the amount of use and the kind of products you allow into your drains will determine how often your septic tank will need to be desludged.

What not to put in your septic tank?

Uncontrolled use of disinfectants or chemical cleansers, especially as is often the case at institutions such as hospitals, schools and hotels, may inhibit the natural bacterial activity. Industrial or other potentially toxic effluent should not be allowed into septic tanks.

Coarse, non-degradable solids such as coffee grounds, cigarette butts, facial tissues, plastic bags, bottle tops, sanitary towels and nappies, must NOT be deposited into the septic tank.

What is a Soakaway?

The soakaway is an underground soil treatment system, which receives partially treated sewage from the septic tank. The soil on a site must be suitable for a soakaway to work properly. Soil that is too coarse, too fine or impermeable, can limit the effectiveness of the treatment system. It is imperative that effluent from a septic tank is not discharged into a river, vlei, etc as it is by no means, in terms of health, fit for animal or human consumption. The size of your septic tank soakaway is determined by the size of your septic tank and the size of your dwelling. It cannot be built near any open water such as a river or vlei because of the possibility of seepage from the soil into the water.


What is a Conservancy Tank?

A conservancy tank is any covered tank without an overflow which is used for the reception and temporary retention of sewage and that requires routine emptying at intervals.

What is a Grease Trap?

Grease traps are commonly used on the waste pipe from the kitchen, with the object of removing as much grease and fat as possible. Grease traps have special merit at a restaurant or kitchen where excessive amounts of fat and oil are likely to be released, which may cause accretions in the sewers or rapid accumulation in the septic tank. In a household the amount of solid matter contributed by the kitchen nowadays is quite considerable and it certainly seems worthwhile to remove the fatty material, as it would reduce the quantity and tenacity of the scum formed in the tank.

The proper function of a grease trap is very much dependant on the regularity with which it is cleaned. The design and construction of grease traps should provide for conditions, which are suitable to allow the fat in suspension to rise and collect at the surface.