If you are like most people, you probably don’t know too much about septic tanks. What are they? How do they work? How often should they be emptied? In this blog post, we will answer all of these questions and more! 

So read on to learn all you need to know about your septic tank!

5 Things You Need to Know About Septic Tanks

1. What is a septic tank?

A septic tank is a large watertight container that is buried underground. Each septic tank design varies but is typically made of concrete, fibreglass, or plastic. 

We use septic tanks to treat wastewater from toilets, showers, sinks, and other household fixtures when a home isn’t connected to the municipal sewer system.

The plumbing from your home transports grey water and sewage into your septic system through an inlet pipe. 

2. How does a septic tank work?

Septic tanks work by collecting wastewater from your plumbing, separating it into layers where it is broken down by bacteria. 

The wastewater then settles into three layers:

  • Bottom layer: The solid waste usually sinks to the bottom and is digested by the bacteria in the tank into sludge.
  • Middle layer: The middle layer is mostly clear effluent water.
  • Top layer: The top layer is called scum and comprises fats, grease, oil, and soap residue.

The sludge and scum remain in the tank, where they are eventually broken down by the bacteria. Once the sludge and scum reach a certain level, you must empty your septic tank.

Here’s how a soakaway treats effluent water:

  1. The effluent water from the middle layer flows out of the septic tank through the outlet pipe. This pipe leads to either a soakaway or an external emptying system. 
  1. Your effluent water flows into a soakaway, a series of perforated pipes buried in the ground and designed to remove pollutants from your effluent water. 
  1. The treated effluent water then leeches out of these pipes into a porous layer of gravel and soil. As the effluent water trickles through these layers, it is naturally filtered and becomes groundwater. 

If you do not have a soakaway, make sure to drain your septic system more often to prevent it from overflowing and contaminating your groundwater.

Cleaning Out Septic Tanks

3. How often should septic tanks be emptied?

Septic tank cleaning should be done depending on the size of the tank, how many people are using it, the amount of wastewater it receives and whether you have a soakaway. 

There is no one size fits all answer to this question, so it is best to speak to a professional plumbing company like Absolute Plumbing to determine the appropriate septic tank cleaning schedule.

If you do not empty the tank regularly, solid waste and scum can build up, causing the tank to overflow. An overflowing tank is a health hazard as it can cause sewage to back up into your home and pollute ground and surface water.

If you live in South Africa, check with your municipality to see if they drain septic tanks for a fee, or you can call Absolute Plumbing to arrange a septic tank drainage service.

Municipality Cleaning Septic Tanks

​​4. How to eliminate septic tank odour?

Septic tanks can sometimes produce an unpleasant smell. If the contents of your tank are acidic, the bacteria won’t be able to digest it, and this causes a build-up of gases.

Regular septic tank maintenance will help you eliminate the odour, so have your tank professionally pumped and cleaned by a registered plumber at least every 3-5 years. More often if you don’t have a soakaway.

There are a few things you can do to eliminate residential septic tank odour:

  • Pump your tank regularly
  • Buy enzymes from the hardware store to add to your toilets and tank
  • Use septic system safe cleaners
  • Have your sewage disposal system professionally cleaned every few years
  • Cover it with a lid with a vent

If the smell is emanating into your bathroom, this may indicate a problem with your septic system, or you may have a blocked drain. In this instance, it is best to call out Absolute Plumbing immediately so we can find and fix the problem.

5. Can septic tanks explode?

It is incredibly rare for septic tanks to explode as most tanks have a vent, and you would need a heat source to cause combustion. They contain a number of gases, including methane, ammonia, and carbon dioxide.

Septic tank gases can be dangerous if they build up in enclosed spaces, so it is vital you ventilate yours properly. Your septic system should have a vent pipe that goes from the tank to the outside of your house. This pipe allows the gases to escape, so they don’t build up and explode. 

Remember, this is extremely rare, but you need to be aware of the risks that accompany any household fixture.

How Absolute Plumbing Can Assist You

Absolute Plumbing can assist with all problems relating to septic tanks in Cape Town, including concrete septic tank leak repair

Our team of professional plumbers are expert drain cleaning specialists and will ensure your plumbing is free from blockages so your wastewater can flow easily into your sewage tank.

Absolute Plumbing offers professional and reliable septic tank installations in the southern suburbs and the greater Cape Town area. We also install conservatory tanks, french drains and soakaways to meet your individual needs. Contact Absolute plumbing today for our septic tank price breakdown.

Installing Septic Tanks


Septic tanks are a necessary part of any home that is not connected to the municipal sewer system. Remember, your tank needs to be emptied on a regular basis and should be appropriately ventilated to prevent any build-up of dangerous gases. 

If you have any questions about septic tanks or need one installed, contact Absolute Plumbing for professional, reliable, and affordable plumbing services. You can also follow our journey on social media for plumbing tips and tricks.

Open chat
Welcome to Absolute Plumbing

How can we help you?