coerco updates

April 2, 2019

10 Frequently Asked Questions on Septic Systems

Septic Systems, Commercial

Below are answers to the most frequently asked questions we get asked about septic systems. 

1. Does my septic tank need to be completely buried?

Yes. Septic tanks must be buried. 

Apart from this, septic tanks must have an access opening capable of being extended to          ground level as well as an inspection opening. This makes it easy to conduct maintenance      regularly. Additionally, the access opening must be watertight to prevent water (e.g.                  groundwater and stormwater) from entering the septic tank.


coerco septic tank about to be buriedCoerco 4,000 litre septic tank. 


2. How deep can my septic tank be buried?

Coerco poly septic tanks are not to be buried more than 500 mm beneath ground level            surface. This is because Coerco septic tanks are engineered and tested to be buried no          more than the said depth.


Coerco's 4,000 litre septic tank about to be buriedCoerco 4,000 litre septic tank. 


3. How do I determine the size of my septic tank?


Generally, a smaller household of, say, 3 bedrooms, will need a smaller septic tank                  compared to a household with 5 bedrooms. Below is a table to help you determine septic        tank size (or capacity).


calculation table for determining septic tank capacity

Source: Health (Treatment of Sewage and Disposal of Effluent and Liquid Waste) Regulations 1974


4. What length of leach drain do I need?

The length of your leach drain is determined by the type of soil and the number of                    bedrooms in your house. Requirements from the Department of Health are outlined in the        table below. These requirements can vary depending on individual council stipulations.

table for determining leach drain length

Source: Health (Treatment of Sewage and Disposal of Effluent and Liquid Waste) Regulations 1974


5. Should a septic tank and leach drain be trafficable?


Coerco septic tanks aren’t trafficable. However, an engineered cover above the buried tank      and an access opening can be installed.

On the other hand, Coerco leach drains can be configured to be trafficable by reinforcing          them with more internal panels.

However, the Department of Health does not allow for leach drains to be installed in                  trafficable areas. Vehicles are too heavy and could damage pipes, not to mention compact      the soil and compromise evaporation. Oxygen also helps the soil around the drain field/            leach field to break down waste, but concrete or asphalt only serves to impede oxygen and      further reduce waste breakdown by microorganisms in the soil.


Coerco septic tank coverSeptic tank cover slab. 


6. How often should my septic tank be pumped out?

A septic tank may be pumped out every 2 to 5 years. However, this can vary depending on      the amount of solid wastes in your tank and the number of people in your household.

For example, a two-person household may require desludging every 8 years.

Apart from this, annual inspection should be done to check for any damage.

If you’re not sure whether your septic tank needs pumping, you can have it inspected by a        certified pumper near you and then get advice as to when (or how often) you should get          your tank pumped again. You can even record this data on paper to make sure you don’t          forget.


7. How do I know that my septic system is failing?

The most common reason for a malfunctioning septic system is a lack of maintenance. For      instance, if your septic tank hasn’t been pumped out for many years, it could likely be full of      sludge which can clog up the pipes.

See here for signs that a septic system is not working properly.

8. How can I avoid septic system failure?

A properly designed and correctly installed septic system is a must. After installation,                regular maintenance is key to ensuring that your septic system lasts a long time.

As a rule of thumb, items that do not decompose easily (this includes food, cotton, plastic,        etc.) must not find their way in as they can cause clogging.

9. Who do I call to de-sludge or inspect my septic system?

Only certified pumpers must de-sludge your septic tank and inspect your entire septic              system, including the leach drain. Your local health district or health department may be          able to provide you with a list of certified pumpers. 

10. Do I need additives/chemicals?

The biological material needed to break down waste is already in the waste itself. For as          long as your septic system is well-maintained and not misused, there is no need for                  additives or chemicals.

septic tanks



Back to top