Wastewater treatment plants

We collect and treat about 1.5 billion litres of wastewater from homes and businesses every day. About 100 million litres of this is recycled every day to:

• water gardens, golf courses and parks
• flush toilets
• wash cars
• fight fires
• use in industry, including at our wastewater treatment plants.

Our wastewater treatment plants use different processes to remove impurities from wastewater. The process used at each plant varies depending on:

• the location of the plant
• where the treated water will be discharged
• whether or not the wastewater will be used as recycled water
• the nature of the plant's catchment area
• the age of the plant.

These factors help shape our tailored environmental protection licences for each plant.  

Advanced water treatment plants

St Marys Advanced Water Treatment Plant is one of the largest recycling plants in Australia. It treats wastewater from Penrith, Quakers Hill and St Marys wastewater treatment plants to produce very high quality recycled water. This recycled water is released into the Hawkesbury–Nepean River at Penrith. This saves water stored in dams for drinking and keeps the river healthy.

We report results of recycled water testing at St Marys Advanced Water Treatment Plant once a year. This is set out in the licence.

Air quality

North Head and Malabar wastewater treatment plants are the largest plants in Sydney. As part of the wastewater treatment process, these plants produce chlorine and hydrogen sulphide gases. We use odour scrubbers to filter the air. This helps us remove these gases and meet our environmental licence requirements for odour. 

Water filtration plants

We operate water filtration plants at:

• Cascades
• Orchard Hills
• Nepean
• North Richmond
• Warragamba.

These plants filter and treat water before it goes into drinking water pipes. The filters are regularly cleaned to remove trapped particles. This keeps them working efficiently.

The backwash water at Nepean, Orchard Hills and Warragamba is recycled within the plants. At Cascades, the clear backwash water is put into Cascade Dam. At North Richmond, the backwash is put into the Hawkesbury–Nepean River. To ensure the local waterways aren't impacted when the backwash water is released, we test for suspended solids and pH.

We collect water samples at the North Richmond plant every 25 days and at the Cascades plant every 90 days. We publish the North Richmond results monthly and the Cascades results quarterly.

Pollution incident response

The way we respond to pollution incidents follows international and Australian standards and guidelines. Read our Water and wastewater treatment pollution incident response management plan (1.2KB) to find out about:

• the steps involved in responding to a pollution incident     
• our incident command structure     
• our hazard identification and risk control procedures     
• our incident management document hierarchy.