Remove, reuse or destroy a septic tank

If you have a septic tank on your property that you no longer need, you can:

  • remove
  • reuse or
  • destroy it.

You can only remove a septic tank once your property is connected to sewerage or other wastewater management system.

Before you remove, reuse or destroy

You must get the contents of the septic tank pumped out by a listed waste handler.

Find a listed waste handler on the Northern Territory Environment Protection Authority website.

The contents must not be discharged above ground.

The waste handler will also:

  • hose down all inside surfaces and
  • remove the leftover wastewater.

If you decide to keep the tank in the ground, the waste handler must first disinfect it.

This can be done by spreading hydrated lime over all internal surfaces.

Don’t go near the tank because vapours in confined spaces can be toxic.

Removing the septic tank from your premises

You must get a licensed plumber and drainer to disconnect the tank from:

  • your premises and
  • the land application area (eg the absorption trenches).

The inlet and outlet pipes on the tank must be permanently sealed or plugged.

Find a licensed plumber and drainer on the Plumbers and Drainers Licensing Board website.

Reusing a septic tank

You can reuse your septic tank to store stormwater.

You must not reuse it as a vessel for:

  • holding water for drinking purposes or
  • any internal household domestic purpose.

Before you begin

Before you can reuse your tank, you must get a licensed plumber and drainer to:

  • disconnect it from the premises and the land application area, and
  • connect an overflow pipe from the tank to where stormwater is discharged.

Once cleaned out and disinfected with hydrated lime, the tank must be:

  • filled with fresh water
  • disinfected with 100 mg/L of pool chlorine (calcium hypochlorite or sodium hypochlorite).

This will provide a minimum 5 mg/L of free residual chlorine after 30 minutes.

However, to disinfect your tank properly, you should get advice from a chemical supplier about:

  • safety precautions
  • dosage and
  • concentrations.

The chlorine must not be neutralised, but allowed to dissolve naturally for at least a week.

During this time, you must not use the water.

After your septic tank is disinfected

You can install pumps to connect the stormwater tank to an irrigation system.

You can only use the stormwater for garden irrigation.

You must not use the contents of the tank for:

  • any internal household purposes or
  • topping up a swimming pool.

You must label the tank and irrigation system ‘not fit for drinking.’

Destroying a septic tank

If you want to destroy a septic tank, you must engage a licensed plumber and drainer to do this.

Read more on how to destroy a septic tank.

Demolishing the land application area

You don't need to demolish land application areas such as absorption trenches or subsurface irrigation areas unless they present a public health or environmental risk.

Collapsed land application areas can be backfilled with clean fill.

Last updated: 30 November 2020

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