Find out about the types of effluent disposal systems used on properties in the area, including septic tanks, leach drains and soak wells.

Primary treatment systems

Primary treatment systems (also known as septic tanks, conventional systems or standard systems) are common effluent disposal systems adopted in the Shire. They usually consist of two concrete or plastic septic tanks, or one large septic tank with a baffle, which drains into alternating leach drains or soak wells.

The minimum capacity of a primary treatment system, treating all wastes, connected to a residential home up to 5 bedrooms, is 3180L. Two septic tanks, 1 x 1520mm in diameter and 1 x 1220mm in diameter, or one large baffled tank of at least 3180L, is suitable.

Leach drains can be concrete or non-concrete. The length of the leach drain required depends on the volume of wastewater, the soil type and the manufacturer of the drain.

Soak wells can only be approved for use in sand.

Secondary treatment systems

Secondary treatment systems (formerly known as aerobic treatment units or ATUs) function like small treatment plants. They produce effluent of a secondary standard which can be used for irrigation. These systems are required to be serviced regularly (usually quarterly) by an authorised service person.

Alternative treatment systems

These systems function as a conventional system but provide an alternative to a standard septic tank and leach drain system. Some alternative treatment systems also provide additional treatment at the disposal area, which may assist with the removal of nutrients from the wastewater. 

The alternative wastewater treatment system industry is growing rapidly, and in the last few years, there have been some innovative systems approved by the Department of Health. 

Like secondary treatment systems, an approved installer is required for the installation. There will be conditions of approval and specific installation requirements that need to be met.

Sometimes, ongoing maintenance is required.

The Department of Health publishes the list of approved alternative treatment systems, including contact details for each system.

Alternative toilets

Alternative toilets are also known as waterless or composting toilets. When applying to use an alternative toilet, the application process is the same as for an effluent disposal system. The proposed system must be one that is on the list of approved alternative toilets on the Department of Health website.

The installation must be in accordance with the conditions of approval for that particular system, so it is important to be familiar with the system and the conditions prior to applying for approval to install. For example, some waterless toilets cannot be approved on small lots (<1000m2) or lots where a sewer is available.

Greywater systems

Greywater is the wastewater from:

  • Showers
  • Baths
  • Handbasins
  • Washing machines
  • Dishwashers
  • Kitchen and laundry sinks.

It does not include toilet waste.

There are two types of greywater reuse systems in WA:

  • Greywater diversion devices (GDD): These systems divert greywater without storage or treatment and can be used via sub-surface irrigation in gardens.
  • Greywater treatment systems (GTS): These systems collect and treat the greywater to a higher standard. The disinfected greywater can be used for irrigation and other applications such as reuse in toilet systems or washing machines.

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