Coastal wastewater treatment plants

There are 11 coastal treatment plants. The three largest are located at North Head, Bondi and Malabar and treat most of Sydney's wastewater, discharging via deep ocean outfalls.

Treatment plant	Treatment level	Dischrg (ML/ day)1	Equivalent population3	Discharge type	Discharge location
Warriewood	Secondary & disinfection	16	59,000	Shoreline	Turimetta Head
North Head	High-rate primary	336	1,240,000	Deepwater	3.7 km from shoreline, 65 m max. water depth, 762 m diffuser zone
Bondi	High-rate primary	130	480,000	Deepwater	2.2 km from shoreline, 63 m max. water depth, 512 m diffuser zone
Malabar	High-rate primary	456	1,690,000	Deepwater	3.6 km from shoreline, 82 m max. water depth, 720 m diffuser zone
Cronulla	Tertiary and disinfection	54	200,000	Shoreline	Potter Point
Bellambi	Wet weather sewage treatment plant	0		Nearshore	Bellambi Point
Wollongong	Tertiary and disinfection	40	199,000	Nearshore	Reuse at Bluescope steelworks . Discharge of remainder via offshore outfall with diffuser zone
Port Kembla	Wet weather sewage treatment plant	0		Shoreline	Red Point
Shellharbour	Secondary & disinfection	16	60,000	Nearshore	Offshore outfall with diffuser zone
Bombo	Secondary & denitrification & disinfection	3.6	13,300	Shoreline	Headland north of Bombo Beach

¹ Average daily dry weather discharge.

² Chemically assisted sedimentation (CAS).

³ Equivalent Population (EP): an estimate of the number of people served by a treatment plant.

⁴ Outfall length is the distance from the shoreline to the end of the diffuser zone.

The smaller coastal treatment plants - Warriewood, Cronulla, Bombo, Wollongong, Port Kembla, Brooklyn, Shellharbour and Bellambi, discharge treated effluent closer to the shore. Approximately 0.5 per cent of Sydney's wastewater is discharged untreated to the ocean at Vaucluse, Diamond Bay and Diamond Bay South.