Rouse Hill Water Recycling Plant

Rouse Hill Water Recycling Plant is one of our 30 wastewater treatment and water recycling plants.

Here, we treat wastewater to tertiary standard, then recycle most of it back to customers for non-drinking purposes such as flushing toilets, watering gardens and washing cars.

It's Australia’s largest residential recycling scheme.

Rouse Hill Water Recycling Plant aerial photograph

Rouse Hill Water Recycling Plant supplies high quality water for non-drinking purposes.

Want to visit a wastewater treatment or water recycling plant?
We offer excursions and technical tours to schools, universities and community groups.

Request an excursion
Location Mile End Road, Rouse Hill
Population served 32,000 properties
Area served All or parts of Rouse Hill, Stanhope Gardens, Glenwood, Kellyville, Kellyville Ridge, Parklea, Acacia Gardens, Beaumont Hills, Quakers Hill, The Ponds and Castle Hill
Amount of wastewater treated each day  24 million litres
Treatment level Tertiary
Recycled water applications
  • We re-use some water on-site for industrial purposes, like washing down equipment and backwashing filters.
  • We supply up to two billion litres of recycled water a year to homes and businesses in the Rouse Hill area for non-drinking water uses. Learn more about water recycling and how you can use recycled water in your home.
Environmental discharge
  • We release excess recycled water to wetlands in Second Ponds Creek.
Amount of biosolids produced each year 10,000 tonnes
Operating license and regulation We operate the plant under three sets of rules:

Primary treatment

Treatment flow diagram Rouse Hill

Treatment flow chart. Select the image to see a larger version.

Primary treatment removes large solids using physical separation processes. Most of the solids removed can be treated for beneficial re-use.


Screens trap and remove large solids, such as paper, cotton tips and plastic, as wastewater flows through.


Large solids, like wipes, food scraps, rubbish, cotton tips and plastic are caught on the screens.

Grit removal

We stir the wastewater rapidly, forcing the water to spiral and create a vortex. The vortex causes grit to spiral to the centre of the tank, separating it from the water.

Secondary treatment

Secondary treatment removes nutrients such as phosphorous and nitrogen using physical, biological and chemical processes. Learn more about Removing nitrogen and phosphorous.

We split the wastewater into two streams. One stream flows to the bioreactor and the other flows to the Intermittently Decanted Aerated Lagoons (IDAL).


We add a high concentration of micro-organisms (activated sludge) to the wastewater. By varying the amount of air in different parts of the tank, we ensure different types of micro-organisms are able to break down nutrients (like nitrogen and phosphorous).

We pump the wastewater to a clarifier. The activated sludge settles to the bottom of the clarifier where scrapers remove it. We recycle some of this sludge back into the bioreactor and treat the rest to produce biosolids.

The treated water from the top of the tank flows to tertiary treatment.

Rouse Hill bioreactor

Micro-organisms break down nutrients in the bioreactor.


We add a high concentration of micro-organisms (activated sludge) to the wastewater.

Like in the bioreactor, varying the amount of air ensures different types of micro-organisms are able to break down nutrients (like nitrogen and phosphorous). In the IDAL, wastewater goes through three stages - aeration, settling and decanting - in one tank, rather than passing through separate tanks.

Rouse Hill IDAL

The IDAL goes through aeration, settling and decanting in the one tank.

Tertiary treatment

Tertiary treatment uses chemical and physical processes to remove very fine solids and disinfect the treated wastewater.

Chemical mixing

We add chemicals that make the smallest particles 'stick' together forming larger 'flocs'. This process is called flocculation.

Tertiary clarifier

When the flocs become large enough they settle to the bottom of the clarifer and are removed.

The treated water flows from the top of the tank to the filters.

Rouse Hill Clarifier

Small particles settle out in the clarifier.


Filters made of layers of sand and coal trap and remove any remaining floc and fine solids.

Rouse Hill fliter

Very fine particles are trapped and removed in the filters.


We use chlorine and ultraviolet light to kill any micro-organisms that can make us sick.

Rouse Hill chlorination

We use chlorine to make sure the treated wastewater is safe.

We use recycled water for a number of different things.

On-site re-use

At our treatment plants, we use recycled water instead of drinking water wherever we can. Our hoses, sprays and filter backwashes all use recycled water.

Residential recycled water

We supply up to two billion litres of recycled water to homes each year to flush toilets, water gardens, wash cars and for other outdoor uses.

Recycled water is supplied to customers through pipes that are separate to the drinking water supply, which is known as 'dual reticulation'. Recycled water pipes and taps are coloured purple to distinguish them from the drinking water system.

Learn more about using recycled water.

Recycling - Rouse Hill - 5530

Homes in the Rouse Hill area can use recycled water on their gardens.

Did you know?
On average, customers in the Rouse Hill recycled water area use up to 40% less drinking water than other customers in greater Sydney.

Environmental flows

We release excess recycled water into man-made wetlands at Second Ponds Creek, eventually flowing into the Hawkesbury-Nepean River.

Running the plant

Eight staff manage, operate and maintain the plant. They collect and analyse water samples, do laboratory testing and manage special projects to keep the plant running safely and efficiently.

Staff at a plant

Staff working on a treatment plant take samples to monitor the plant's performance.

Maintaining the plant

There are three types of maintenance required to keep the plant operating: preventative, planned and reactive.

Maintenance type Description Example
Preventative Prevents a break down Oiling a motor
Planned Replacing equipment as it reaches the end of its useful life, before a break down Replacing a worn motor
Reactive Fixing equipment that has unexpectedly broken down Repairing a motor