Exmouth water source planning

Water Corporation is currently licensed to take up to 1.032 billion litres per year from the Exmouth borefield, which relies on heavy episodes of rain in summer/autumn, and winter rainfall, for replenishment. Climate modelling forecasts hotter temperatures, more extreme weather events, and less reliable rainfall for the region, which may impact groundwater availability.

Exmouth is expected to require an additional 1.5 billion litres to secure the water supply to 2060.

Water Corporation has licenses with the Department of Water and Environmental Regulation to abstract water from two groundwater subareas. This is through 6 bores within the Exmouth Town Groundwater Subarea and 28 bores within the Exmouth Central Groundwater Subarea, which is located further south of the townsite.

These licenses are due for renewal in January 2027. There are three other groundwater sub areas in Exmouth, to the north, south and to the west of the existing borefield, from which Water Corporation does not abstract water.

Demand for water in Exmouth has accelerated in recent years, alongside population growth and increased tourism.

To manage demand for water in Exmouth, we have an active demand management program in place to help improve water efficiency. This has recently included:

• plumbing and irrigation services to help customers find and fix leaks
• comparative use letters to encourage waterwise behaviours
• waterwise product offers, including the free waterwise showerhead swap program
• marketing and education activities

We’ve also recently completed a roll-out of new smart water meters to all properties in Exmouth. Customers can now log in to their Water Corporation online account to view their water use and identify hidden leaks. We continue to work with high water users in Exmouth to manage demand and promote water efficiency.
Demand for water is still expected to be close to, or exceed, our current groundwater license limit in coming years until a new source is available. As a result, Water Corporation will also be making a license allocation increase application to DWER, to temporarily increase the amount of water we can supply from the existing groundwater borefield, until a future desalination plant is able to be delivered.  

Department of Water and Environmental Regulation are responsible for all water and environmental regulation. They determine how much water can be taken from groundwater and surface water resources, while safeguarding the sustainability of the resource and protecting the water dependent environment. 

Water Corporation is the principal supplier of water, wastewater, drainage and some bulk irritation services in Western Australia to homes, businesses and farms. We are regulated by DWER and Department of Health. Supply of water is licensed by the Department of Water. 

On average, new sources typically take up to 5-6 years to deliver from the current stage we are at, through to construction and commissioning. Exmouth has complex ecological and cultural values that may impact this, and all timeframes are subject to funding and government approvals. 

As we progress our investigations and engagement, we will be able to improve our estimate of a delivery timeframe. 

We are committed to keeping the local community updated and providing opportunities for feedback. We’ve engaged extensively with stakeholders, and the community, since 2023.

This has included meetings and correspondence with Government agencies, the Shire of Exmouth, Traditional Owners, environmental and commercial groups, fisheries stakeholders, and face to face opportunities for the local community.

Our project team will next host face to face drop-in sessions in Exmouth in August 2025, so we can hear your thoughts and answer any questions you may have. 

We’ll continue to work with stakeholders and the community as we progress towards a decision on the most appropriate location for future infrastructure. 

See the map of the groundwater investigation areas below

Seawater desalination works by separating water molecules from seawater. First, seawater is screened and pre-treated to remove large particles like seaweed and sand. Next, the seawater is fed through reverse osmosis membranes, where water molecules pass through, and the remaining seawater becomes saltier. About 40-45% of the seawater becomes freshwater for drinking and the remaining 55-60% is brine.  The brine is nearly twice as salty as the original seawater. 

• Location: The intake is usually placed in deep water where the water quality is good and environmental impact is minimal. The intake pipeline does not have to be near the plant. However, the longer the pipeline, the higher the construction and maintenance costs.
• Design: It is designed to handle large volumes of water and withstand harsh marine conditions.
• Environmental impact: Care is taken to minimise impacts to marine life by using protective structures, such as velocity caps (to slow the intake speed) and screens (to keep out larger marine life).  We complete habitat surveys to identify areas of bare sand. Low disturbance installation methods such as horizontal directional drilling are considered.

• Location: The diffuser is generally located offshore, away from sensitive marine habitats and in deep water where brine can be effectively dispersed.  The diffuser pipeline does not necessarily need to be near to the plant; however, the longer the pipeline is the more it costs to construct.
• Design: The diffuser is designed to minimise environmental impacts, often using multiple diffuser ports to increase brine dilution and spread. Instead of releasing all the salty water from a single point, the ports spread it across multiple locations, promoting faster mixing and more efficient dispersion over a larger area.
• Environmental impact: Brine dispersion modelling is done prior to construction to ensure the diffusers are designed for the location. This ensures we comply with the Environmental Protection Authority’s environmental quality framework for marine discharges. We complete habitat surveys to identify areas of bare sand. Low disturbance installation methods such as horizontal directional drilling are considered.
• Regular environmental monitoring of the water quality and marine habitat is completed to ensure compliance with licence conditions and environmental standards.

In seawater desalination plants, brine is the salty byproduct returned to the ocean. It is nearly twice as salty as seawater because about 40-45% of the freshwater is removed. Brine may contain very small amounts of food-grade chemicals like anti-scalants and cleaning agents. They are used to keep the membranes working efficiently. Only chemicals approved by the Department of Health for use in drinking water are used. 

Environmental monitoring and data collection starts before a site is selected for any seawater desalination plant. This information helps us design and position the infrastructure to minimise environmental impact. It also forms part of the environmental impact assessment and approval application that is sent to the Regulator.  
Monitoring of the marine environment includes:

• water quality monitoring of the ocean including existing contaminants, salinity, temperature and dissolved oxygen levels (up to two years) 
• benthic habitat mapping, which is the process of identifying and mapping underwater environments, specifically the seafloor and the organisms that live there. This includes mapping of reefs, troughs and freshwater seeps
• targeted surveys of marine flora and fauna, where required.

In addition to monitoring, we also complete the following studies:

• desktop review of existing historical data and literature 
• ecotoxicity testing in a laboratory, which tests whether the brine could have an impact on the larvae and adults of local marine species 
• we engage with Traditional Owners and other community and industry stakeholders to identify their key uses, and values and concerns.

July 2025

Following extensive investigations and stakeholder engagement, seawater desalination has now been selected as the preferred new water source for Exmouth. 

A new seawater desalination plant will cater for the impacts of climate change and population growth. It will secure Exmouth's water supply for the future.

Throughout the next stage of planning, we’ll further progress investigations to confirm a location for a new seawater desalination plant. See the map below of the potential desalination locations identified in early planning. 

 

You can drop by to see the project team at Ross Street Mall, near Exmouth IGA:

• Friday 8 August, 2:30pm-4:30pm
• Saturday 9 August, 9:30am-11:30am

Our team will be there to listen and answer any questions you have. 
Or, email the Community Engagement team to share feedback or ask a question.

18 June 2025

In December last year, we advised we were starting marine investigations in Exmouth Gulf. These investigations gather information to identify a preferred location for a potential Exmouth Seawater Desalination Plant (SDP), including marine pipelines. The information gathered is also used as part of an Environmental Impact Assessment.

In May, we started seabed (benthic) habitat mapping and freshwater seep surveys. The early results of these investigations guide us in choosing a favourable site, particularly by avoiding sensitive marine habitats like coral and seagrass.

Other investigations include:

• seawater quality sampling and profiling (12-24 months)
• continuous water quality monitoring using submerged loggers (24 months)
• current and wave data collection (up to 12 months)

Regular monitoring will take place for up to 24 months. There will be extra monitoring following certain weather or environmental events, such as after a cyclone or during coral spawning.  

5 December 2024

We will soon be commencing marine investigations in Exmouth Gulf. These investigations will help us gather information to identify a preferred location for potential Exmouth Seawater Desalination Plant (SDP) pipelines, understand the operating risks of the proposed location and to inform an environmental impact assessment. Additionally, the water quality data will inform potential treatment processes required for a proposed SDP.

Work will begin in December 2024. Further sampling and data collection will take place on a quarterly basis for up to 24 months, with some potential event-based sampling following certain weather or environmental events. Check out our marine investigations fact sheet on the webpage for more information. 

10 September 2024

It was great to meet with so many of you at our community drop-in sessions at the end of August. We spoke to over 130 people over the two days and got really great insight into your thoughts on the investigation areas for the groundwater and desalination options.

If you weren't able to attend either of the sessions, please get in touch using the contact details on the webpage and we would be happy to provide further information. 

 

 

12 August 2024

The project team will be hosting two drop-in sessions in Exmouth on these dates. 

• Ningaloo Centre, Mandu Mandu West Room on Friday 30 August from 12.30pm - 4.30pm and
• Ross Street Mall, near Exmouth IGA, Saturday, 31 August from 8am - 12pm.  

Drop by to find out more about these investigations, we look forward to seeing you there!  

8 May 2023

Department of Water and Environmental Regulation (DWER) and Water Corporation have commissioned an aerial electromagnetic (AEM) survey in Exmouth to detect groundwater sources and support future water supply planning work. 

This information will be used to support DWER’s water allocation planning and Water Corporation’s future water source planning investigations for the Exmouth water supply scheme.
Full details via the Department of Water and Environmental Regulation (DWER) aerial electromagnetic (AEM) survey (May/June 2023) document.