EPA pollution monitoring

Take a look at our data reports

We test water quality at our wastewater treatment plants, water filtration plants and at the advanced water treatment plant every month. We publish the results of our tests within 14 days of the last test result becoming available. If test result summaries don't meet the limits in our environmental protection licences, we explain when, why and to what extent.

Who issues environmental protection licences?
The NSW Environment Protection Authority (EPA) issues the licences to us. You can ask to see the data we collect under the licences by emailing  epareports@sydneywater.com.au.

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.  

Plant name EPA licence and limits EPA yearly summaries EPA monthly summaries




Castle Hill




Hornsby Heights



North Head

North Richmond



Quakers Hill



Rouse Hill


St Marys



West Camden

West Hornsby



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.


EPA licence and limits EPA yearly summaries EPA monthly summaries

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. 


Plant name EPA licence and limits EPA yearly summaries EPA monthly summaries


North Head









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.


Plant name EPA licences and limits EPA yearly summaries EPA monthly summaries


North Richmond

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.