Standards Septic Systems

Conventional or standard septic systems have the following standard requirements:

  • A primary and secondary septic tank with wastewater flowing from the secondary tank, through a diverter box to leach drains;
  • The WA Department of Health has approved a number of plastic and non-plastic septic tanks which may be suitable for your proposal. Many of these consist of one tank with a baffle to separate the two chambers;
  • The leach drains will be a pair of the appropriate length in either concrete or plastic. This guideline to leach drain lengths will assist in determining the length that will be required for your proposal. In certain situations a reduced system may be permitted, for example where sewer will become available to the property within the next three years.
  • Leach drains can be concrete or other material. The WA Department of Health publishes a list of approved plastic leach drains
  • Minimum setbacks that must be achieved during installation of a standard septic system:
    • 1.2m from the septic tank to any building, footings, retaining wall or boundary;
    • 1.0m between the primary and secondary septic tanks;
    • 1.8m from any leach drain to any septic tank, any other leach drains, any building, footing or retaining wall, any sealed or paved area or any boundary;
    • 30m from any leach drains to any well or bore intended for human consumption; and
    • 6m from any leach drain to any sub-soil or open drainage system
    • 1.2m from the base of the leach drain to the highest known winter water table 

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