Does your property rely on sewerage disposal by septic tanks or other on-site sewerage treatment facilities?

There are legal requirements that apply to installing and maintaining these systems.

This page provides a bit of information about different systems, how they work and what approvals are needed.

What is an on-site sewerage facility (OSSF)?

An on-site sewerage facility (OSSF) is a system that stores, treats and disposes of household toilet wastewater, on a property. There are many different types, most common are septic systems, aerated wastewater sewerage treatment plants and sand filter systems.

The treated wastewater must be pumped to a designated ‘land application area’ which is a portion of land set aside to take the treated water. It is pumped by either an irrigation system or through absorption trench systems. The size of land needed depends on the type of system.

Do I need approval for a new or changed system?

Yes. All on-site wastewater systems need approval (plumbing permit) from Council, including for:

• Installing a new system
• Making an addition/extension to an existing system
• Converting from a septic system to a different type of treatment system We have developed a checklist to help explain the steps in detail. Key things to note are:
• A qualified site and soil evaluator will be able to assist you with identifying what type of effluent disposal system is most suitable for your property.
• A qualified wastewater designer will need to prepare the design of the on-site sewerage facility and the application material.
• Council’s permit will come with conditions that will need to be met, including for installation and maintenance.

What maintenance is likely to be involved?

Ongoing maintenance is essential! Maintaining a treatment plant or sand filter is a legal requirement under the Plumbing and Drainage Act 2018. The steps involved vary depending on the type of system and can involve:

Septic systems:

• Desludging the tank unit every five (5) years by a professional pumping contractor
• The land application area must have the grass mowed and plants maintained
• Regular clean out of grease trap
• Protect the land application area from vehicles.

Aerated wastewater treatment plants and sand filter systems

• Are serviced by a licensed service agent in accordance with manufacturer requirements and Council conditions, and generally;
• Aerated wastewater treatment plants – every 3 months
• Sand filtration systems – every 12 months.