Recover, recycle and reuse

How we give new life to wastewater

Our water resource recovery facilities use conventional and advanced technologies to process wastewater, eliminate waste and recover resources. All facilities recycle water, reuse by-products or generate some of the energy they need to do their job. Some do all three. We're committed to reducing the environmental impact of what we do to help mitigate climate change.

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Recycled water

Renewable energy

Biosolids

A water resource recovery facility displaying this symbol recycles water.

Recycled water

Everyone in Greater Sydney should have a reliable, drought-resistant water supply. Recycling and reuse allow us to be less dependent on rainfall to provide water to customers. Recycled water lets us make more water available for residents and businesses to use during drought.

Wastewater is treated to a quality where it can be returned to the environment or recycled, meeting the requirements of our environment protection licences. The recycled water we supply to customers meets the high standards of the Australian guidelines for water recycling.

All our water resource recovery facilities put wastewater through a multi-step treatment process to remove impurities. It is treated to suit:

  • the environment (creek, river or ocean) that will receive it
  • how it will be reused.

There are 5 treatment levels in our recycled water process. Our facilities provide different treatment levels depending on how the water will be used. These include:

  • primary treatment
  • secondary treatment
  • tertiary treatment
  • advanced treatment
  • disinfection and pH balance.

Recycled water provides around 96% of the water needed to operate our water resource recovery facilities – around 125 billion litres of recycled water a year.

A water resource recovery facility displaying this symbol produces renewable energy.

Renewable energy

We're always looking for ways to reduce our carbon footprint and use alternative and renewable energy sources. Water resource recovery facilities generate different types of renewable energy from their processes as they treat wastewater. They use it to help power their operations.

The different types of renewable energy we recover at our facilities are:

  • renewable electricity from hydroelectricity, co-generation and solar energy
  • renewable gas, also known as biomethane.

Hydroelectricity

We harness the power of the treated wastewater on its way to a deep ocean outfall. It's captured by our hydroelectric generator at North Head Water Resource Recovery Facility. North Head is currently the only water resource recovery facility that produces hydroelectricity. We also produce hydroelectricity in our water systems at Prospect and Woronora.
 

Cogeneration

Cogeneration is the process of turning waste methane gas (biogas) into electricity and heat. Biogas is naturally created during wastewater treatment. Bacteria break down wastewater sludge in anaerobic (without oxygen or air) digesters. This helps power our water resource recovery facilities.

These water resource recovery facilities have cogeneration units: Bondi, Cronulla, Glenfield, Liverpool, Malabar, North Head, St Marys, Warriewood and Wollongong.

We're also investigating co-digestion to increase the amount of energy generated at our water resource recovery facilities. Co-digestion is the process of turning food waste into energy by adding it to our anaerobic digesters along with the wastewater sludge. We've trialled co-digestion at Bondi and Cronulla. The next facility to receive food waste for co-generation will be Liverpool.

Solar energy

We've installed solar systems and solar hot water systems at several of our water resource recovery facilities. These include Brooklyn, Glenfield, Liverpool and Wollongong. We also use solar energy at many other sites, including water and wastewater pumping stations. We'll continue to invest in solar energy across our facilities.
 

Biomethane

We've partnered with Jemena to install a biogas upgrader at Malabar Water Resource Recovery Facility. Excess biogas not used for cogeneration is treated to produce renewable gas, or biomethane, that can be supplied to Jemena's customers via the local gas network.

Overall, renewable energy generation can produce about 20% of Sydney Water's energy needs – enough to power over 15,000 homes each year. That's a tremendous saving for customers.

A water resource recovery facility displaying this symbol produces biosolids.

Biosolids

Biosolids are a nutrient-rich fertiliser converted from the organic solids wastewater solids – or sludge – produced during wastewater treatment. They're a rich source of phosphorus and nitrogen used in agriculture, forestry, composting and land rehabilitation.

These water resource recovery facilities produce biosolids: Bingara Gorge, Bombo, Bondi, Cronulla Gerringong-Gerroa, Glenfield, Hornsby Heights, Liverpool, Malabar, North Head, Penrith, Picton, Quakers Hill, Richmond, Riverstone, Rouse Hill, Shellharbour, St Marys, Wallacia, Warriewood, West Camden, Winmalee and Wollongong. The remaining water resource recovery facilities transfer wastewater sludge to one of the listed facilities to be processed.

Producing biosolids helps us reduce our environmental footprint by:

  • minimising the discharge of solids to our oceans and rivers
  • recycling a valuable resource that helps minimise disposal to landfill
  • reducing the amount of chemical fertilisers used on farms
  • producing carbon-neutral biogas used to generate renewable energy to help power our water resource recovery facilities.

We produce around 180,000 wet tonnes of biosolids from Sydney's wastewater in a year. That's over 9,000 busloads.