Sydney Water owns 29 sewage treatment plants, 28 of which it operates and one (Gerringong-Gerroa) operated by Veolia.
There are 14 inland plants that discharge into the Hawkesbury-Nepean, Blue Mountains, South Creek, Berowra Creek and Cattai Creek catchments.
These STPs are currently being upgraded to advanced tertiary standard to protect the sensitive Hawkesbury-Nepean waterways.
Sydney Water is also working as part of a cross-government approach to review future options for further improving water quality and providing for environmental flows.
| Treatment plant | Treatment level | Discharge (ML/day)1 | Equivalent population2 | Discharge location |
| Hawkesbury-Nepean catchment | ||||
| North Richmond | Tertiary (Includes additional Phosphorus removal & disinfection) |
0.9 | 3,760 | Redbank Creek to the Hawkesbury River |
| Penrith | Tertiary (Includes additional Phosphorus & Nitrogen removal & disinfection) |
22.4 | 96,800 | Boundary Creek to the Nepean River. Future reuse planned. |
| Picton | Tertiary (Includes additional Phosphorus removal & disinfection) |
1.5 | 10,200 | Re-used on-site for agricultural irrigation. Precautionary discharge to Stone Quarry Creek |
| Richmond | Tertiary (Includes additional Phosphorus removal & disinfection) |
2.2 | 7,800 | Reused for irrigation at the UWS Richmond Campus, excess overflows to Rickabys Creek |
| Warragamba | Tertiary (Includes additional Phosphorus removal & disinfection) |
0.6 | 2,670 | Warragamba River |
| West Camden | Tertiary (Includes additional Phosphorus removal & disinfection) |
10.7 | 49,700 | Reuse at Agricultural Institute.Remainder discharged via Matahill Creek to the Nepean River |
| Brooklyn | Tertiary and disinfection using ultraviolet light and membrane bioreactor technology. | 0.4 | 500 | Hawkesbury River estuary |
| Blue Mountains catchment | ||||
| Winmalee | Tertiary (Includes additional Phosphorus & Nitrogen removal & disinfection) |
16.0 | 56,300 | Unnamed creek to the Nepean River |
| South Creek catchment | ||||
| Quakers Hill | Tertiary (Includes additional Phosphorus & Nitrogen removal & disinfection) |
31.1 | 144,400 | Breakfast Creek to Eastern Creek. Future reuse planned. |
| Riverstone | Tertiary (Includes additional Phosphorus removal & disinfection) |
1.7 | 8,400 | Eastern Creek to South Creek |
| St Marys | Tertiary (Includes additional Phosphorus & Nitrogen removal & disinfection) |
33.5 | 139,700 | Unnamed creek to South Creek. Future reuse planned. |
| Cattai Creek catchment | ||||
| Castle Hill | Tertiary (Includes additional Phosphorus removal & disinfection) |
6.5 | 24,900 | Cattai Creek |
| Rouse Hill | Tertiary (Includes additional Phosphorus & Nitrogen removal & disinfection) also includes ultra violet irradiation & super chlorination for reuse water |
15.3 | 63,100 | 1. Recycled back to households for non-potable use 2. Excess discharged to Second Ponds Creek via wetlands to Cattai Creek |
| Berowra Creek catchment | ||||
| Hornsby Heights | Tertiary (Includes additional Phosphorus & Nitrogen removal & disinfection) |
6.7 | 28,300 | Calna Creek to Berowra Creek |
| West Hornsby | Tertiary (Includes additional Phosphorus & Nitrogen removal & disinfection) |
12.0 | 53,500 | Waitara Creek to Berowra Creek |
| Gerringong-Gerroa catchment | ||||
| Gerringong-Gerroa | Tertiary (Includes additional Phosphorus removal & ozonation, microfiltration, activated carbon & disinfection) |
0.7 | 11,000 | Reused for on-site agricultural irrigation. Excess is discharged to sand dune systems. Once sand dunes reach capacity, excess is discharged to Crooked River. |
1 Average daily dry weather discharge.
2 Equivalent population (EP): an estimate of the number of people served by a treatment plant.