Projects under this method can earn Australian carbon credit units (ACCUs) by reducing methane amounts released into the atmosphere. This is done by changing how domestic, commercial or industrial wastewater is treated.

When to use this method

This method may be suitable for your business if you:

  • capture and burn methane from wastewater treatment
  • convert methane into biomethane as a natural gas substitute in Australia
  • treat domestic or commercial wastewater in an open lagoon that's more than 2 metres deep and existed before 24 April 2014
  • replace your open lagoon with an anaerobic digester that captures methane produced during wastewater treatment
  • a biogas upgrading system that refines the gas into biomethane as a natural gas substitute.

You can find more information by referring to our full domestic, commercial and industrial wastewater method guide


To be eligible for this method, your project must replace an open wastewater treatment lagoon with an anaerobic digester.

Eligible open wastewater treatment lagoons must:

  • be more than 2 metres deep
  • have treated wastewater before 24 April 2014
  • have been in existence before 24 April 2014
  • be used to treat any combination of eligible domestic, commercial or industrial wastewater for 12 months prior to project application.

Your anaerobic digester must transfer captured methane to a combustion device, which uses the methane as fuel. It must include a biogas collection system and the equipment required to transfer the biogas to the combustion device.

If your project involves producing biomethane, you must install new biogas upgrading systems.

You must also meet general eligibility requirements for the Australian Carbon Credit Unit (ACCU) Scheme.

Relevant legislation

  • Part 3 of the Act
  • Section 8-11B of the method


This method excludes wastewater from farming or primary production, such as piggery or dairy manure. However, it does include wastewater generated during the processing of primary products, such as processing of pork or milk.

Method requirements

This method was varied on 2 January 2022 to:

  • introduce new eligible project activities to allow projects to upgrade biogas into biomethane that can be used as a natural gas substitute
  • allow projects to claim abatement associated with producing biomethane for use that results in destruction of waste methane, known as conversion abatement
  • allow projects to claim abatement associated with producing biomethane that displaces natural gas use, known as displacement abatement.

If you have a current domestic, commercial and industrial wastewater project, you may be able to transfer it to the varied version of this method. You can apply to transfer through the Client Portal via Online Services.

Project activities under this method must:

  • measure and calculate your current emissions levels
  • replace an open wastewater treatment lagoon with an anaerobic digester that’s either a covered lagoon or an engineered biodigester
  • collect and combust captured methane, through a flare, boiler or internal combustion engine that generates useful heat or electricity
  • collect biogas to burn in a combustion device or be upgraded into biomethane.

Biomethane should be used as a natural gas substitute in Australia:

  • on-site
  • at a different location
  • by injecting it into the gas grid.

You can use flares, boilers or internal combustion engines as your methane combustion device. Other types of methane combustion devices need approval.

You can find out more about running biomethane project activities by referring to our biomethane method package simple method guide. 

Relevant legislation
  • Section 8–11B of the method

For non-biomethane projects under the wastewater method, the crediting period is 7 years.

If your project produces biomethane, its crediting period is 12 years, minus any time the project has previously earned ACCUs for methane destruction.

Relevant legislation
  • Part 5 of the Act

Abatement is calculated by subtracting project emissions from baseline emissions.

Project emissions result from energy used to run your project. This includes emissions from:

  • fuel and electricity use
  • the anaerobic digester, combustion device, and biogas upgrading systems
  • the end management of digestate, which is the solid material that remains after wastewater treatment.

Baseline emissions are emissions that would occur if wastewater was treated in an open lagoon instead of an anaerobic digester. They can be calculated by measuring the amount of:

  • organic material in the wastewater that would have been treated
  • methane sent to the combustion device.

If you have done historical sampling to work out baseline emissions, you can use either option above.

Historical sampling involves collecting wastewater samples from the lagoon before replacing it with an anaerobic digester.

If your historical information doesn’t meet method requirements, or you don’t have historical information, then you can only use option 2 (methane sent to a combustion device) to calculate your baseline emissions.

Relevant legislation
  • Part 4 of the method

You must monitor:

  • quantities of ineligible materials and eligible wastewater treated by your project
  • volume and methane content of biogas sent to combustion devices or biogas upgrading systems
  • volume of fuel and electricity used by the project
  • wet weight of treated digestate.

If you aren't able to monitor a parameter as required by Section 45 of the method (non-monitored period), you must determine value of the parameters following the Section 46 requirement.

You must also remember to meet general monitoring requirements of the Act.

Relevant legislation
  • Part 17 of the Act
  • Section 45–46 of the method.

You must keep records according to general record-keeping requirements of the Act and rule.

Relevant legislation
  • Part 17 of the Act
  • Part 17 of the rule
  • Section 43A–43C of the method

You must report any periods when meeting monitoring requirements isn't possible and when your project doesn't meet the current NGER Measurement Determination. This report must state:

  • why the current NGER Measurement Determination wasn't used for the reporting period
  • the dates when a project used a previous version of the NGER Measurement Determination.

You must remember to also report according to the reporting requirements of the Act and the rule.

Relevant legislation
  • Part 6 of the Act
  • Part 6 of the rule
  • Section 42–42C of the method

We provide you with an audit schedule when your project's declared.

You must provide audit reports according to this schedule.

We schedule at least 3 audits and additional audits can be triggered.

For more information on audit requirements, refer to our audit information.

Relevant legislation
  • Part 19 of the Act
  • Part 6 of the rule