Water

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

Includes:

• 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.