Orchard Hills Water Filtration Plant

Filtering drinking water

Orchard Hills Water Filtration Plant filters rainwater collected in the stunning Lake Burragorang, which sits behind Warragamba Dam. The plant filters 120 million litres of water every day in summer!

Facts and figures

Location: Orchard Hills.

Population served: 200,000 people.

Areas served: Greater Penrith, including St Marys, Emu Plains and the Lower Blue Mountains. Occasionally, water from Orchard Hills may be pumped further up the Blue Mountains for emergencies, like bushfires. Find out where your water comes from in our water network.

Source water: Warragamba Dam.

Amount of water filtered in winter: Average of 65 million litres each day.

Amount of water filtered in summer: Average of 120 million litres each day.

Maximum capacity: 215 million litres each day.

Year the plant was built: 1993

Treatment type: Direct filtration

Find out more about the plant in Orchard Hills technical data (139KB).

Flow chart

Filtration steps

We filter 100% of your water to make sure it's safe to drink straight from your tap.

Our water filtration processes can be different at each of our plants. We tailor the process to suit the quality of incoming water.

Orchard Hills receives water from the local, natural catchment of Warragamba Dam. WaterNSW’s monitoring expertise ensures the best quality source water is selected. Because this water is high quality, we use a modern filtration process called direct filtration.

Direct filtration means the water can be filtered straight away and doesn’t need lots of additional treatment steps before or after filtering. It also uses less chemicals and energy than other types of filtering processes.


We use a fine mesh screen to remove debris, like twigs and leaves from the water.

The mesh screen acts like a sieve, trapping the debris as the water passes through.

Rapid mixing

We add solutions to the water to aid the filtration process.

The solutions:

  • adjust the pH
  • make small particles ‘stick’ together to form larger ‘flocs’, making them easier to filter out. This is called coagulation and flocculation.

We use a large, rapid mixing paddle to spin the water around very quickly and mix the solutions.


We use filters made of tightly packed beds of sand and crushed coal to trap and remove the floc.

We clean our filters several times a week and continuously monitor their performance to ensure your water quality always remains high.

Learn more about Drinking water filtration (494KB) .

Protecting the quality

We carefully balance the pH of the water.

We add small amounts of chlorine to protect the water from harmful pathogens, keeping it safe for us to drink.

As a final step, we add small amounts of fluoride to the water as a safe and effective way of preventing dental decay. It’s not part of the filtration process, but is added under the advice of NSW Health.

Learn more about water quality and filtration.

Do a water audit

Find out how water efficient your school is and how to manage water for the future.

Come behind the scenes

Want to visit one of our sites? We offer free excursions and technical tours to schools, universities and community groups.