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Frequently Asked Questions

1. What is the difference between a Septic Tank, a Conservancy Tank and a Digester?
A Septic Tank has two or more chambers with a 110mm outlet to a French drain soakaway. Since the internal baffles, which create the chambers, prevent any solids from flowing between the chambers, the quality of the effluent is superior to that of a digester. A septic tank does not need to be desludged.
A Conservancy Tank has an inlet but no outlet. When full, It is emptied by 'honey-sucking' with a tanker truck. A Digester is a single-chamber tank with a 50mm outlet to a French drain soakaway. Since digestion takes place in the single chamber, the 50mm outlet and French drain often get blocked by undigested solids. The Digester needs to be desludged at least once per year.
2. How do I know what size tank to purchase?

The size of a septic tank is determined by the volumetric flow. A key factor is the retention time. This is the time it takes for the bacteria to break down the solids into fluids. The minimum time is 24 hours. Therefore, the capacity of the tank must be large enough to hold the contents for the retention period, without the system being flooded and washing the contents out too quickly. A further influence is the use of a single or dual pipeline. Contact us for help in calculating the actual volumetric flow and, therefore, the correct size tank.
3. How far away from the building should I place the tank?

The design of every house or building, with regards to the positioning of baths, toilets, kitchen, driveways, pool, etc. varies considerably. The slope of the ground is another factor to be taken into account. International research has proven that the most effective slope on a sewer line is 1:40. That is, a drop of 250mm for every 10 metres of pipe length. Ideally, the tank should be located between 4 and 10 metres from the building, so that the tank is positioned just below natural ground level. If the lids are fitted properly and they are covered by a mound of soil, there should be no odours from the system. This is also important for access to the system as well as reducing the pressure on the tank from the weight of the surrounding soil.
4. Do I need a 'starter', like a dead chicken or chemicals, to get the system working?

Human waste contains all the bacteria necessary to break down the solids to fluids and keep the system working. Adding a dead chicken or similar to the system is not only unnecessary, but may well poison the system before you even start. The chemicals touted on the market are a powdered form of bacteria and whilst they do no harm, they are actually a waste of money.

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5. What items should not be allowed to enter the system?
A septic tank is a living biological system. Any substance which is anti-bacterial or not bio- degradable, should never be allowed to enter the system. Therefore, substances such as Jik, Jeyes Fluid, toilet blocks that hang in the toilet bowl or cistern, turpentine, paint thinners, paint and even certain other cleaning materials such as Handy Andy can poison the system. When shopping, it is advisable to check the label to ensure that the product is 'septic tank friendly' or 'bio-degradable'. Ladies sanitary towels, disposable nappies, condoms or any other foreign matter should be disposed of with household solid waste. Avoid newspaper entering the system as it does not break down sufficiently and will block the system.
6. How will I know if the system is poisoned?

A healthy system will form, within three to six months of installation, a khaki-coloured blanket on the surface of the water in the first chamber. When this blanket turns grey or black in colour the system has been poisoned. In addition, the odour from the system will become quite strong.
7. What do I do if the system is poisoned?

The first thing to do is have the system 'honey-sucked'. After emptying, the tank(s) should be rinsed out with a high pressure hose to remove whatever caused the poisoning. This rinsing water should then also be sucked out. Caution should be taken not to dislodge the baffle from it's groove. The system can then be used as normal. Important however, is to determine which cleaning materials or items disposed of in the toilet, may have caused the poisoning. If found, they must be removed from use. No foreign materials should be flushed down the toilet.
8. The tank(s) is overflowing, what must I do?

An overflowing tank points to a blockage in the outlet or French drain. To determine if the French drain is under pressure, drill a tiny hole (2mm) in the top of the outlet pipe. If the French drain is blocked or saturated, the water will form a fountain out of the hole. The water will just trickle out if the French drain is functioning well. No French drain lasts forever. Depending on the soil type, clay vs turf vs ouklip vs sandy soil, and the way in which the French drain was constructed, it can last 12 to15 years before the surrounding ground becomes totally saturated. The solution is to move the position and create a new French drain some distance from the saturated one. If space is limited, this could become a problem. Ensure that there is a grease trap in the gulley immediately outside the kitchen where the pipe comes through the wall. Cleaned regularly, this will prevent the fats and oils from forming an impervious layer on the walls and bottom of the French drain.

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9. The system floods regularly, what is the problem?

A recurring problem indicates a saturated French drain. If soil type and space limitations are not conducive to building a new French drain, then the alternative is to consider installing an on-site sewage treatment plant. The benefit of this is that the treated water can be used for watering lawns, gardens, vegetables, fruit trees etc. and will be absorbed by the plants or evaporate on the surface. These systems are particularly suited to ecologically sensitive areas, or where the soil type is impervious to water. Recent legislation (2012) also prohibits the use of septic tanks and French drains, in certain areas, because of the pollution to the underground water table and the poisoning of boreholes.

10. Can I use the effluent from a septic tank to water the garden?

No. Untreated effluent from a septic tank is highly toxic and a danger to humans and animals. Contact with this water can cause severe diarrhoea, dysentery, typhoid fever and cholera amongst other undesirable afflictions. Leaks or floods from the system should be dealt with immediately.

11. The system smells, why?

There will always be an odour associated with sewage, however, it should be so slight as to be virtually indiscernible. Check that the lids on the tank(s) are fitted tightly. If this does not cure the problem, check for any leaks in the pipes, tanks or French drain. An important cause of strong odour is a poisoned system. Check that the contents of the first chamber are khaki coloured. If grey or black in colour, the system is poisoned and must be 'honey- sucked' and rinsed out to remove whatever caused the poisoning.

12. Is a Grease Trap really necessary?

Whilst a grease trap is not an absolute necessity, it will certainly prolong the life of the pipelines and particularly the French drain. The fats and oils from dish washing sit in solution in the hot soapy water of a hand wash or dishwasher. As soon as this water is released down the drain it starts to cool, and the fats and oils congeal in a sticky white paste on the inside of the pipes. Just as happens with cholesterol in the human body, this eventually blocks the pipes. Similarly, the walls of the French drain get coated with a layer of fat and oil which prevents the water from soaking away into the soil. If cleaned regularly, the grease trap is probably the single most important component of a system, to greatly reduce potential problems and extend the trouble-free life of the whole system.

13. What are the benefits of a dual pipe system?

There are two main benefits to a dual pipe system. Firstly, and most importantly, it reduces the risks of poisoning the system, as all the grey water from baths, basins, kitchen, etc. goes straight into the French drain without entering the septic tank. Therefore, only the cleaning materials for the toilets need to be biodegradable. Secondly, since the greatest volume of water is grey water, the carrying capacity of a given septic tank is almost doubled. A dual pipe system should be designed and built from scratch with the house. To retrofit such a system is not impossible, but will be rather costly.

14. Can I install a septic tank system myself?

Septic tanks and French drains are usually built and installed by plumbers. However, installing such systems is not rocket science and, providing attention is paid to certain common sense factors, the successful diy installation is quite straight forward. The website sections on septic tanks and French drains give detailed information on how to install the whole system. Alternatively, we are only on the other end of a telephone line.

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