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What is decommissioning of a septic tank?

What is septic tank decommissioning?

Septic tank decommissioning is the process of making a septic tank inactive and treating the system with chemicals to ensure it doesn’t affect public health and safety. Once the property has been connected to the municipal sewer connection or a new system installed, the old onsite wastewater treatment system needs to be decommissioned.

What happens during septic tank decommissioning?

Decommissioning a septic system is not a straightforward process and definitely not a DIY project. The harmful chemicals present in the septic tank are toxic and can be fatal. For this reason, you need to take help from a licensed liquid waste contractor. 

So what happens during septic tank decommissioning?

  1. The plumbing and electrical connections to the septic system are disconnected and capped. 
  2. The effluent and sludge present in the tank is pumped out. 
  3. The tanks are treated with Aglime or Hydrated Lime to disinfect and kill the contaminants. Lime also stops the bad odour coming from the tank. 
  4. The tank is then drained by making a few holes on the bottom of the tank.
  5. The leach drains and soak wells are also drained.
  6. Empty tanks are removed but if it is not possible, the concrete lids and tank are broken and filled with solids like sand, concrete and gravel. are buried below ground level. 
  7. Tank is buried below ground level and the surface is compacted to prevent settling as it could cause a sudden collapse. 
  8. The septic contractor will document the whole procedure and provide receipt for verification by the council officers.
Septic Tank Decommissioning - Sunshine Coast Council
Septic Tank Decommissioning - image Sunshine Coast Council

Why is decommissioning of septic tank important?

Septic tanks are the breeding ground for toxic gases harmful to our health and environment. Old septic systems can become weak with time because of corrosion and can eventually collapse causing injury and even death. To prevent any unfortunate accidents it is critical to get your septic system decommissioned immediately. If you have an abandoned septic system, contact your local wastewater contractors.

When should you decommission the septic system?

  1. If the ownership has changed, the decommissioning should occur within 60 days after the change of ownership.
  2. If the use of property changes
  3. If the building is to be constructed above the septic system or if the building is to be built closer than 1.2 metres to the septic system.
Septic Tank Decommissioning - Sunshine Coast Council
Septic Tank Decommissioning - image Sunshine Coast Council

Who can decommission a septic system?

Septic systems need to be pumped out and cleaned by a licensed liquid waste contractor.  Our licensed and highly qualified team can safely and efficiently decommission your septic system. Express Wastewater is a locally owned, family operated business servicing South-East Queensland. If you have a septic system that needs to be decommissioned, contact us today on 1300 722 517. Alternatively complete our online booking form and we will get in touch with you.

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Why Use Express Wastewater Solutions?


    Because we are not a manufacturer and not tied to one particular system we can always offer the best solution for your wastewater needs.


    Because we do this every day we have developed a close knit expert team for every step of the process – from plans and council paperwork to excavations, electrical and plumbing. We handle it all to make the whole process as stress free and quick as possible.


    Most people have never installed a home sewerage treatment plant and don’t know the next step, that is why we offer a free 30 minute phone consult with one of our experts to point you in the right direction.


    We handle your wastewater installation from start to finish we can deal with all the trades, council everything so you don’t have to worry about a thing.


    Have peace of mind knowing that Express are licensed, insured professionals that will do your job right the first time.


    Not sure what system is right for you, or want to know if your system is working properly? Just give one of our friendly wastewater experts a call and they will be more than happy to help.


    We will always look to repair your system rather than replace it if it does not need to be, which will generally save large amounts of money sometimes up to and over $10,000.