Sydney’s climate‑proof water backbone: Inside Sydney Desalination Plant’s ability to expand

As Sydney’s only major rainfall‑independent source of drinking water, the Sydney Desalination Plant (SDP) helps provide Sydney with optionality and additional system resilience. The Plant is built to complement Sydney’s dam storages and the treatment network, giving Sydney Water flexibility when they need to conduct critical maintenance or face water‑quality challenges or water supply shortages. It is part of the supply system and is designed to enhance the overall drinking water system resilience for Sydney.

In this blog, Matt Blaikie, General Manager Business Optimisation at SDP discusses how the Plant is future proofed and prepared for expansion.

How is Sydney Desalination Plant future proofed?

The Plant was designed to meet Sydney’s drinking water needs, now and in the future. The intake and outfall tunnels supplying seawater, and the pipeline connecting to the Sydney Water network are sized to allow us to double the Plant’s capacity. Major civil infrastructure has been constructed at the Plant, and environmental and planning approvals are in place. We have land set aside on our site in Kurnell, ready to go when we are asked by Government to expand – allowing us to expand without any disruption to the rest of the city or to our on-site conservation area.

An expanded Plant would continue to run on renewable energy, as the existing Plant does, and use proven reverse osmosis membrane technology while embracing innovation and targeting incremental improvements for reliability and efficiency.

We are well prepared for future expansion of the Plant because from our perspective, planning early means we can provide reliable high quality drinking water for homes and industry in an efficient and cost-effective manner.

What specific problem is the expansion meant to solve, and why now?

Extreme weather events, droughts and floods are occurring more often, and it’s hard to predict when they will occur or how long they might last. For us, expansion is about providing additional resilience to Sydney’s drinking water supply. Not only for drought response, but to provide a stable, climate‑independent supply of drinking water to Sydney that reduces the risk of disruptions to supply and keeps daily life and jobs moving. Additional rainfall independent capacity also helps Sydney Water efficiently manage ageing infrastructure and water‑quality issues in dams by giving the water supply network breathing room for critical maintenance.

Further to this, industry is increasingly becoming reliant on water to keep technology running, thus a stable and resilient water supply system is critical. One good example of this is the recent increase in the construction of data centres. We want to support crucial industries to expand and continue operating even when water supplies are challenged.

In response to why now, planning and building major infrastructure such as the expansion takes years and years. Acting early delivers better, considered, and more affordable outcomes than rushing to solve an immediate problem in a crisis.

How much additional capacity are you able to provide?

We will work closely with the Government, Sydney Water and other key stakeholders to understand the optimal solution. However, we are able to fully duplicate the existing Plant’s capacity.

Today, we are able to supply up to 15% of Sydney’s drinking water needs. This is substantially lower than other capital cities around Australia. To compare, Melbourne and Adelaide have up to 33% and 40% of rainfall independent capacity in their drinking water supply system through desalination. Doubling our capacity would allow us to supply up to 30% of Sydney’s drinking water needs and also provides Sydney with additional system resilience against the effects of droughts, floods and water‑quality issues – for example, when there are bush fires, the quality of the water in the dams can be impacted due to bushfire debris washing in, which means alternate drinking water sources will be crucial to maintaining consistent supply.

What technology will be employed in the expansion?

We are always open to new ideas and innovation; however, our starting premise is to stick with what works. Primarily, membrane‑based reverse osmosis desalination will again be utilised, which is more energy efficient than thermal processes, and has proven performance here in Sydney and in Australia in general.

We expect the expansion to largely replicate our current design but will work closely with technology and construction experts through a competitive tender process to implement smart, incremental upgrades. These could include improvements to our pre‑treatment process to protect the membranes and enable additional efficiencies, changes to the reverse osmosis membrane configuration, and more digital monitoring and data‑driven control so we can respond faster and run more reliably.

We like to think of it as refining a well‑tuned engine rather than reinventing it. We’ll also continue our robust and proven intake and discharge design and operations strategies to protect the environment. The goal is simple: dependable, efficient desalination that integrates seamlessly with the existing plant and the wider drinking water network.

Can you explain how renewable energy will power the expansion?

In compliance with our environmental and planning approvals, we’ll consider a range of options to contract green electricity, so the Plant’s output is matched with clean generation. Currently we source all our energy needs from Capital Wind Farm.

We’ll keep improving efficiency too. Today’s reverse osmosis membrane technology is already more energy efficient than that was built 10 to 15 years ago, and we’ll apply smart controls to squeeze more drinking water out of every kilowatt. We’re also exploring practical options like increased onsite storage to smooth demand and support network reliability.

The aim is simple: deliver a climate‑independent drinking water supply while minimising our environmental footprint, keeping costs sensible and efficient, and ensuring reliable operations for Sydney’s homes, businesses, and essential services.

Is the expansion designed to complement or substitute future water recycling projects?

Complement, absolutely, not substitute. Sydney needs a portfolio of varied solutions. Efficient use and demand management, recycled water, rainfall‑dependent sources like dams and rivers, and rainfall‑independent sources like desalination.

Our expansion adds a reliable, climate‑independent backbone that gives Sydney Water more reliability and flexibility. We fully support initiatives that expand reuse and reduce wastage. By planning desalination alongside recycling and other smart solutions, we can ensure we build a more resilient drinking water network, so homes, businesses, and essential services have the water they need, whatever the weather.

When do you expect the expansion to start? Are you ready to go?

We have completed extensive preparations and will continue to monitor the market and technology trends so we can move quickly when asked. The Government has asked us to consider expansion a couple of times, and we have completed the groundwork – site investigations, conceptual designs, how a duplicate Plant will fit on our site, and keeping our on‑site conservation area untouched – which is really important to us.

Timing ultimately depends on Government approvals and broader water security planning. If approved, you’re looking at about a six‑year program, with roughly three and half to four years of construction and commissioning. We’ll carefully schedule any short shutdowns needed to connect the new Plant and aim to avoid disruptions during periods of high demand if possible. The goal is to start early enough to deliver capacity before or at the time when Sydney needs it.

Customer FAQ

How much additional capacity is able to be built?

• A full duplication of the existing Plant’s capacity, taking SDP from supplying around 15% of Sydney’s drinking water today to about 30%, strengthening the city’s insurance against droughts, floods and dam quality issues.
• The existing Plant can deliver 250 million litres per day (ML/day) on average, so at double the size this will be 500 ML/day

Will desalination replace water recycling projects?

• No – we expect desalination will complement recycling, demand management and dams, although the exact mix is a decision for Government.

How will you power the expansion?

• The Plant’s output will be powered with 100% renewable energy.

How will the marine environment be protected?

• We already have a proven and robust seawater intake and discharge design that includes dispersion systems, operational strategies and ongoing monitoring that are used to protect marine life and meet our environmental approval requirements.

Will the on‑site conservation area be affected?

• No, the expansion footprint is planned to avoid the conservation area, using land already set aside on site.

Will SDP operate when dams are full?

• Yes, SDP continuously operates. We can ramp up or down production to support maintenance, manage water quality events, and maintain system reliability, even when dam levels are high. By remaining operational, the plant retains this flexibility to respond quickly, and support Sydney Water as needed.

What is the timeline?

• Subject to Government approvals, the program is around six years, including roughly three and half to four years of construction and commissioning.

Will there be construction impacts?

• There will be limited construction impact as much of the infrastructure outside the Plant’s site has already been built. Work will be scheduled to minimise disruption to the community and the water supply network.