Wastewater Disposal and Recycling
Treated wastewater is recycled or discharged to waterways or land.
In the greater metropolitan area, 81% of all treated wastewater is safely discharged to the ocean and about 5% recycled. 4% recharges groundwater aquifers and the balance (not managed by the Water Corporation) is disposed through septic tank systems.
Most treated wastewater from major plants is discharged to the ocean from outlets at Ocean Reef, Swanbourne and Cape Peron.
Ocean discharge is most commonly used around the world to discharge treated wastewater from larger coastal cities. The wastewater is treated to a standard to protect ocean water quality. It can be an environmentally acceptable and economical method, available all year round.
Of the major Australian cities only Sydney has longer outlets, but they discharge primary treated wastewater. Adelaide has tertiary treatment but only short outlets, while Brisbane discharges tertiary treated wastewater to the river, and Melbourne has shoreline discharges of secondary treated wastewater.
Perth compares very favourably with its major wastewater treatment plants discharging highly treated (tertiary) wastewater through long (greater than 1 kilometre) ocean outlets.
The Kwinana, Gordon Road, Halls Head, Caddadup, Two Rocks and Yanchep wastewater treatment plants recharge groundwater with treated wastewater. In Mundaring, the wastewater is discharged to a stream in winter and used to irrigate public open space in summer.
In the Perth - Mandurah area, recycled water from our wastewater treatment plants is used:
- for processes within the wastewater treatment plant;
- to provide water for industry at Kwinana and Pinjarra; and
- for the irrigation of public open space.
A residual of the wastewater treatment process is biosolids that is recycled (as a soil supplement for agricultural use) or disposed to landfill.