Wastewater management

Wastewater management systems in building control areas

If you want to install a septic tank or other wastewater management system (WMS) in a building control area, you must follow certain rules.

Before you install

Systems in building control areas:

  • are regulated by the Department of Infrastructure, Planning and Logistics and
  • must comply with the Building Act 1993.

You can check if your property is in a building control area on the NT Land Information System website.

Read more about building control areas.


Property owners and professionals have responsibilities around the WMS installation process.

Property owner

As the property owner, you must make sure the WMS is installed and certified by the right professionals.

Read below to find out who can install and certify a WMS.


It is up to the installing and certifying professionals to ensure the system meets the following:

For more information about the WMS process and technical requirements, read waste management systems in building control areas PDF (343.4 KB).

Who can install your WMS

A WMS must be installed and maintained by a licensed plumber and drainer.

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

Who can certify your WMS

All systems must be certified by a building practitioner.

Choosing the right practitioner will depend on:

  • the size and complexity of the system and
  • whether it is installed with other building works.

If your plumber and drainer is also a building practitioner, they may be able to certify the WMS.

Check with your plumber or building certifier.

Systems that treat less than 2,000L of wastewater a day

If your WMS has product approval and will treat less than 2,000L of wastewater a day, you can use one of the following building practitioners:

  • certifying plumber and drainer
  • certifying plumber and drainer (design) or
  • certifying engineer (hydraulic).

To find a registered building practitioner, search the Public Register of Building Practitioners.

Systems that treat more than 2,000L or are complex designs

You must engage a certifying engineer (hydraulic) if your WMS is:

  • likely to treat more than 2,000L of wastewater a day
  • a complex design and does not have product approval or
  • a community WMS.

How to install

The process for installing a WMS depends on whether you want to install it:

  • alongside other works or
  • on its own.

Install a wastewater system alongside other works

To install the WMS at the same time as building a house, industrial or commercial development, it must be included as part of your building permit.

After the WMS is installed, your plumber and drainer must contact Building Advisory Services (BAS) before the works are covered.

Before granting an occupancy permit, the building certifier may need:

  • a compliance certificate for the WMS and
  • any referenced plans.

Install a wastewater system on its own

To install a WMS without any other building work, for example replacing or upgrading an existing system, a permit for plumbing-only works will be included on the building record.

Your plumber must do the following:

  • contact BAS:
    • before starting work and
    • after installation - before the works are covered
  • ensure a compliance certificate is:
    • completed by a building practitioner and
    • submitted to BAS within seven days of the completed work to be kept on the building record for your property.

If your plumber is also a registered building practitioner

If your plumber is also a registered building practitioner, such as a certifying plumber and drainer, they may be able to issue the compliance certificate.


For more information, contact BAS.

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Last updated: 28 April 2021

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