Water use, sustainability, and efficiency by choosing quality systems and materials, and providing environmentally friendly solutions.

Design checklist

Use this step-by-step to guide design of an on-site wastewater treatment system.

These are the stages of an on-site wastewater treatment system design process as set out in AS/NZS 1547:2012 On-site domestic-wastewater management.

Stage 1: Feasibility study

Determine requirements by preliminary:

  • discussion with system suppliers
  • identification of site conditions
  • discussion with regulatory authorities.

Stage 2: Evaluation and investigation

Includes soil evaluation for permeability and drainage capability, and site investigation to identify:

  • gradients
  • site boundaries
  • building positions
  • runoff
  • stability
  • groundwater conditions
  • location of nearby wells, springs and watercourses
  • vegetation
  • climatic conditions.

Stage 3: Selection system

Consider the:

  • number of occupants
  • site conditions
  • local authority regulatory requirements.

Stage 4: Design distribution system

Must include:

  • uniform, effective and continuous distribution
  • an area that can be controlled and maintained.

Stage 5: Approval/consents

Obtain as required from regulatory authorities for:

  • location
  • system specification
  • operation
  • maintenance
  • monitoring.

Stage 6: Installation

In accordance with:

  • approved design drawings and specification
  • manufacturer’s instructions
  • certification as required by the regulatory authority.

Stage 7: Operation and maintenance


  • providing an operations and maintenance manual
  • keeping records of all servicing/inspections/remedial actions
  • carrying out regular inspections/cleaning
  • having a service and maintenance manual with the supplier (for AWTS/ASTS)
  • maintaining the land application area.