Belmont desalination plant

Belmont was selected as the best site for the desalination plant for a number of reasons including:

• ability to connect to our water system
• proximity to the ocean
• low levels of community disruption and impacts due to the relatively remote location
• Hunter Water owns the land
• construction costs were lower than for other sites.

The site also allows the discharge of brine (the remaining salt water from the desalination process) to the ocean via the existing outfall at the nearby Belmont Wastewater Treatment Works.

Work to build the plant started in late 2024 and will take up to four years to complete, assuming the weather is fine and there are no major issues.

Work on infrastructure to support the plant is expected to start soon, including building two new water mains and upgrading existing reservoirs to integrate desalinated water into our network.

We estimate that the cost to design and build the permanent plant is $530 million, including the plant itself and required network upgrades. This investment includes measures to ensure the desalination plant will be an enduring asset for future generations and remain resilient to the impacts of climate change.

Desalination is the process of removing dissolved salts and other particles from seawater. Key features include:

• Direct ocean seawater intake system – seawater from the ocean enters an intake pipeline through a low velocity intake structure located above the seafloor about 1 km offshore. The seawater flows along the intake pipeline to the seawater intake well located at the plant site. The pipeline will be installed under the ocean floor and Blacksmiths Beach using a tunneling method.
• Pre-treatment – Water is pumped from the seawater intake well to the pre-treatment plant, where coarse filters are used to remove larger particles, like sand. The seawater is then filtered through ultra-fine membranes to remove smaller particles.
• Reverse osmosis – The cleaner seawater is then forced at high pressure through almost one thousand reverse osmosis membranes, which act as very fine filters, to remove dissolved salts and other minerals, leaving only pure water. The pure water is extracted and seawater concentrate is left behind. About 42 per cent of the seawater becomes drinking water.
• Final treatment – The pure water is treated to meet Australian Drinking Water Guidelines. The drinking water then travels through pipelines to join the Hunter Water supply network.
• Seawater concentrate – The remaining seawater concentrate, also known as brine, is about twice as salty and about one degree warmer than the ocean. It will be pumped to the existing Belmont Wastewater Treatment Works (WWTW) ocean outfall, where it would be carefully returned along with wastewater effluent, through a large pipe that lies beneath the seabed. The treated effluent and seawater concentrate is dispersed using specially designed diffusers which return the seawater concentrate to normal salinity and temperature.

The seawater concentrate (brine) from the desalination process will be carefully released back into the ocean through the existing Belmont WWTW ocean outfall using specially designed diffusers. Our assessment is that the volume of brine is not expected to significantly impact marine life around the outfall or passing through the area.

Like water sourced from a dam and treated at a water treatment plant, water from the desalination plant will be treated to meet Australian Drinking Water Guidelines, which include criteria for the aesthetic quality of drinking water in addition to criteria for the protection of health

Hunter Water proposes to install a combination of rooftop and ground mounted solar at the Belmont Desalination Plant site to meet a portion of the plant’s energy requirements. The plant’s remaining energy requirements will come from the electricity grid. We will procure renewable energy to minimise the plant’s environmental impact.