Septic Tanks


Tropical Waste Services demystifies the functions of the ubiquitous septic tank and provides this practical information pamphlet to help with the understanding of how a septic tank works, and how to obtain the best perforFmance from it.

Like cars and phones, you probably use and rely on your septic tank daily, and have not considered the day that it will stop working.

Septic tanks need some simple and basic preventative maintenance to keep them functioning efficiently for long periods of time. Eventually your tank will need the contents removed when it nears or has reached its full holding capacity and starts to perform badly, or fails to perform at all.

This is normal.

We hope that you find the information of value to maintain an efficient septic system.


Septic tanks work with the help of anaerobic bacteria (little critters that don’t need oxygen), to break down the edible (YUK) matter, and are in need of very little maintenance, except that they do need to be cleaned every two to five years. Some waste floats (Scum), and forms a crust, which indicates a healthy system, and some sinks (Sludge).

The cleaner water flows from between these layers to the drain-field. As the scum and sludge layers build up over time, the clear water (retention zone) is reduced, and eventually the sludge is flushed into the drain-field. This is why we suggest the Septic Tank be cleaned periodically.


The drain-field or Reln Drain is the final disposal area for all your household wastewater. They work in three ways, absorption (into the ground), transpiration (by plants), and evaporation.

Any sludge discharging from the Septic Tank into the soakage area eventually blocks the pores in the soil, slowing the absorption process, resulting in the trench’s failure, as absorption is the major process of the three.

Tropical Waste warns their clients to look after their Septic system, as the cleaner the water that goes into the drain-field; the longer the system will last. When the drain-field does fail, the only sure fix is to install new trenches in another area.


Septic tanks are meant to be full to their operating capacity.

When we say yours is full we mean full of sludge and scum, and most probably needs emptying.
Otherwise, if the stench is unbearable, all the good bacteria are probably dead and a fresh start is required. Or if the toilet is slow to flush away, (its giving you prior warning here), or won’t flush away at all, the tank is most likely at its full capacity.

The cleaning of the Septic Tank is the best option, and often cheaper than hiring a plumber, as most blockages are easily cleared at the same time as the tank is emptied.


From years of field experience, based on a family of four, with average use, we suggest that septic tanks should be pumped out between three and five years, to keep the system functioning smoothly. Ideally, pump out the tank BEFORE it blocks up, as prevention is definitely better than the cure. Have the condition of the tank checked at the same time! Your licensed contractor can do this for you, usually at no extra charge.

The common myth that “I’ve never had to have the Septic pumped out before”, reflects an unfortunate attitude of neglect. Another way of looking at it is, “if it ain’t broke, don’t maintain it”. We prefer to think of it like servicing your car. It is much wiser to check the oil before the motor seizes.


Tropical Waste Services sealed vacuum tankers collect the Septic Tank waste and transport it to our licensed sewage treatment plant for safe disposal. This process is strictly monitored by the Health Department and The Environmental Protection Authority (EPA). Tropical Waste Services is an approved EPA waste transporter and we comply with set standards and regulations.


Avoid chemicals. Synthetic cleaners and anti-bacterial chemicals kill off the useful bacteria required to rapidly break down and naturally decompose organic substance in your Septic Tank. This breakdown process is essential for healthy Septic Tank operation. Cleaning chemicals and blue dye disinfectants entering Septic Tanks via the toilet bowl or other means, interfere with the simple decomposition process by killing off the useful bacteria.


Unattended youngsters take delight in flushing whole toilet rolls, toys, clothes, little sisters and other stuff.


Apart from inconvenience when it comes time to clean out the Septic Tank, it is illegal to build over a Septic Tank or its drain-field with verandas, carports, concrete or paving. Some properties are sold leaving the new owners to “find the Septic Tank”.


Do Not go overboard with excessive amounts, as this could cause problems with the natural breakdown process.


Ladies sanitary consumables should not be disposed of via the toilet. A separate waste receptacle should be provided where necessary. Sorry girls, but these things, along with disposable nappies, float, never break down and take up a huge amount of space in any Septic Tank, and really need to be disposed of elsewhere.


Fill the Septic Tank three quarters full of clean water. It is normal for it to smell a bit until the bacterial colony re-develops. If the smell persists, flush a cup full of raw brown sugar into the system via the toilet bowl, once a week.


Do Not plant trees with aggressive water seeking root systems anywhere near your Septic Tank or disposal area. Some trees are notorious offenders. Check with your local nurseryman as to suitable species to plant. Generally short lived natives are better than long lived trees and palms. We don’t live in a desert ourselves, but it is best that common-sense prevails here.


These small on site plants have the bonus that the effluent is treated to the stage where it is suitable for re-use in irrigation, and if necessary, even to be used as the cistern water to actually flush your toilet. They do need regular maintenance if they are to function properly, as they have a primary chamber, which is really a septic tank, a pump chamber which also needs cleaning to remove sediments, and most use chlorine tablets in the final process of treatment, before the effluent is pumped out to the irrigation area.


During periods of extreme wetness, as experienced occasionally during the summer months, you may experience trouble with your septic system. You will not be alone.

This is due to the complete inundation of the soil, therefore preventing the normal evaporation and transpiration needed for your septic to function properly. Even septics on high and dry (normally) blocks have this problem in extreme wet seasons. There is generally little we can do to help you at these times, because the water re-enters the septic from the soakage area as quickly as we can pump it out.

If we try to empty a fibreglass tank, there is also the risk that the tank could collapse inwards from the pressure on it from the groundwater in the higher than normal water table. Generally wait until the rains have slowed and the tide has gone out a bit, if you are still having trouble, then call us, as sometimes the inlet pipe clogs while the water table is way up.


Wet wells are like another smaller tank downstream of your septic tank. They have an electric pump that operates automatically, on demand, to pump the effluent to a remote soakage area. Anyone with a wet well system will generally not have any problems with a high water table in the Wet Season, as they effectively isolate the septic from the groundwater.

Usually installed on lower blocks, they are also used to gain the legal distance between the septic and your water supply bore. We always vacuum the wet well clean when we empty your septic as it is surprising how much silt travels through and settles in the wet well. The pump is not designed to pump this sediment. They are a very good and efficient system. The only downside is that you have another electrical device to maintain and replace when it stops working.


Constantly dripping taps or toilet cisterns that need re-washering, can help to overload any septic system. The constant inflow of water is not needed by the soakage area. Fix them yourself or get a plumber to do the job for you. Air Conditioner condensate lines should not be directed to your sewer either.


The general rule of thumb is; if they are safe to use, they are probably not effective; and if they are effective, they are probably not safe to use. There is no quick fix or substitute for proper operation and maintenance of a septic system. Many additives agitate the solids that should sink or float, suspending the solids and allowing them to be flushed into the drain-field, where they clog the pipes and pores in the soil, leading to complete or partial failure of the system.

Septic systems are biological systems and must have living bacteria to work. However, no special seeding is needed to get them started, as the simple act of using the system will provide all the bacteria necessary. Yeast, manure, dead cats or other animals will not develop the colony of bacteria any quicker down the toilet with system blockage being the end result.

Be aware of the havoc they can cause.