A septic tank is a holding tank for sewage that may comprise either a single or double chamber. Effluent from this tank then enters a soak away or leach field where treatment occurs.

Wastewater enters the septic tank and is allowed to separate into three distinct layers usually over a period of two days: • scum - floatable solids, fats, oils & grease • sludge – heavy (settleable) solids • effluent - liquid wastewater found between the scum and sludge layers and which is relatively free of solids. Anaerobic bacteria present partially decompose the sludge and reduce the volume of solids within the septic tank. However, sludge eventually builds up and this has to be pumped out.

* based on a pump out period of 4 years in accordance with tts 16: 80: 400 (1991).

Generally, our septic tanks should be pumped every 4 years based on maximum occupancy. However, depending on the water usage and the amount of waste entering the system, this may vary. Choosing a larger tank than is necessary can also decrease the frequency of pump outs. Inspection of the tank should take place every 12 -18 months to determine the depth of both the scum and sludge (should not exceed 0.5 meters).

Our septic tanks carry a 10 year limited warranty against manufacturer’s defects. This warranty may become void if the tank is not used in accordance with the manufacturer’s specifications.

Currently two types of septic tanks are manufactured: fatboy and rhino. The fat boy septic tanks are spherical and come in two sizes (500 & 800 gallons). These septic tanks have a single compartment and an effluent filter, which is located on the outlet. The rhino septic tanks are rectangular in shape and come in three sizes (600, 750 & 1500 gallons). These have a double compartment separated by an internal baffle wall. Only the 600-gallon rhino tank has an effluent filter on the outlet.

A soakaway is a drainage pit filled with stones that diverts water into the surrounding soil.

Septic tank effluent enters the pit and is temporarily stored until it gradually infiltrates into the sidewall soil. One of the first things to consider when choosing a site for a soakaway is the water table. It is not uncommon for the water table to rise during the wet season and to fall during the dry season. In waterlogged sites, it is often found that the water table is exceptionally high (i.e., near the surface). Clay soils are also unsuitable for soakaways since they become waterlogged quickly. In instances mentioned previously, a soakaway is just not going to work, therefore alternative dispersal systems are necessary e.g. Digesters.

A digester is a secondary treatment unit that treats effluent from the septic tank.

Bacteria naturally reduce the sludge volume during the digestion process and may either require the use of oxygen (aerobic digestion) or not (anaerobic digestion). The most obvious results of this treatment include odor & color elimination. This tank can be used as an alternative where soakaways are not an option and the effluent can be discharged into a rubble drain for final treatment.

Anaerobic digesters utilize bacteria that decompose biodegradable material in the absence of oxygen. This usually occurs in a sealed tank, which prevents gaseous oxygen from entering the tanks. Over a period of time, solids reduction is achieved and the effluent is directed into the soil for final treatment. The anaerobic process is simple and less energy intensive.

Aerobic treatment units are small-scale sewage treatment units that use oxygen for the digestion process to occur. This is usually in the form of aeration via air pumps along with the associating diffusers to inject and circulate air inside the tank. Electricity is therefore required for operation. Effluent from this unit is of a high quality and can be directed into a chlorinator, uv light or the soil.

Digesters are recommended for areas with a high water table and areas that are prone to flooding, since soakaways are likely to fail. They also enable development on difficult sites and can remedy existing malfunctioning systems.

While you get a limited warranty, once installed according to the manufacturer’s specifications and proper maintenance is undertaken, a septic tank can last up to 30 years.

Once the tank has not been installed or used, then minor damage up to 4 inches can be repaired via plastic welding. If the damage is significant then it is advisable to purchase a new septic tank.

We have various brochures on the installation procedure for each type of septic tank that state the dimensions of the hole to excavate as well as what material to use for backfill.

Generally, 3/8" rounded gravel (pea gravel) is recommended. In areas with a high water table, the base should be cast in concrete to prevent the tank from shifting. The tank cover and effluent filter port should never be covered with backfill, soil or concrete. This should always be easily accessible for cleaning and inspection.

A lift station is a chamber that contains a submersible pump and is usually installed below ground to transfer sewage effluent. Lift stations are necessary in situations where gravity flow cannot be achieved i.e. Over long distances or above ground.

The air pump is an essential part of the aerobic digester/ aerobic treatment unit. This is responsible for the elimination of odors and treatment of the effluent. The size air pump may vary depending on the number of persons who will be using the system.

A general inspection is recommended every 6 months for an aerobic system where the filter from the air pump is cleaned and the system is checked for damages. An annual servicing is mandatory and the same inspection as outlined before must be undertaken as well as servicing the air pump

Uv or ultraviolet light is an invisible electromagnetic radiation that can destroy microorganisms. A uv light usually consists of a uv lamp and a flow chamber through which water flows. As the water flows past the lamp, microorganisms are exposed to ultraviolet radiation and are destroyed. Uv is safe and effective, achieving a kill rate of 99.99% for harmful bacteria & viruses.

A riser is an extension, threaded on both sides that screws onto the access opening of the septic tank. The septic tank cover can then be screwed onto this riser at the top. Risers are necessary where the septic tank cover is lower than the surrounding topsoil. This allows the cover to be easily accessible for cleaning and inspection.

Greywater is all the wastewater from bathrooms, sinks and laundry. It does not include water from the toilet or kitchen sink due to the raw food particles present.

Greywater can be directed into a septic tank however the tank size required will be a lot larger but other problems can arise:

• if a soil absorption system is being used (soakaway), the increased volume of water flowing through this system can overload the treatment capacity of the soil. This results in premature failing of the soakaway.
• if too many detergents and harsh cleaning chemicals enter the septic tank since these can kill the bacteria present. This is of particular concern in aerobic systems, which rely on naturally occurring bacteria to treat effluent.
• more wastewater means less retention time in the septic tank and less settling of solids, resulting in faster failure of drain fields /leach fields.

Water softener backwash contains high level of chlorides and kills microorganisms in the tank and also sedimentation of solids.

Undigested food particles take longer to break down and take longer to degrade. A garbage disposal unit increases the amount of solids in a septic tank by as much as 50%, resulting in frequent pumping out. If a garbage disposal unit is discharging into a septic tank, then the size of the septic tank has to be at least twice the original size.

• excessive fats, cooking oils and grease should not enter the septic tank. These should be trapped in a grease trap.
• paints, solvents and motor oil.
• fertilizer, pesticide, garden & harsh cleaning chemicals
• diapers, sanitary napkins, tampons, condoms
• plastics
• enzymes or additives.