We’re planning for our water future to ensure the Central Coast has a resilient and sustainable water supply, now and for future generations.
Over the past year we’ve had meaningful conversations with the Coast community to understand their values around water and their views on the different water supply and demand option types that we were considering.
We took this feedback, combined it with technical studies and assessments, and developed the draft Central Coast Water Security Plan.
The draft plan was then placed on public exhibition from 31 August until 12 October 2021. During this time, the community were invited to:
- review the draft plan
- watch our informative video below, which breaks down the plan in eight minutes
- take a look at our factsheets, located in this page’s document library
- check out our frequently asked questions, located at the bottom of this page
- post a question on our online Q&A board
- attend a 20-minute meeting with one of our technical experts
- provide feedback or a formal submission on the draft plan using our online guided submission form
We are now reviewing the feedback we received on the draft plan before finalising the plan later in the year and submitting the plan to the Department of Planning, Industry and Environment for their review and approval.
Click here to sign up to be notified when the plan is finalised.
Water supply and demand options factsheets
Technical paper factsheets
What is the Central Coast Water Security Plan?
The Central Coast Water Security Plan is the long-term water strategic plan for the Central Coast region which aims to ensure we have sufficient water into the future. The plan has been developed in collaboration with Hunter Water Corporation and Department of Planning, Infrastructure and the Environment. It replaces the existing WaterPlan 2050 document with updated information, research and modelling for water planning on the Central Coast.
As the Central Coast grows, so does the demand for water. However, our current infrastructure can only supply us with a limited amount of water, so we need to address ways to grow our supply, to meet our future demand. We need to plan for new supplies well in advance to allow for them to be developed in time, so we are ready to accelerate the plan if we experience shocks such as drought.
The plan includes a series of actions to reduce the amount of drinking water we use, increase water supply to homes, business and industry to meet the growing population on the Central Coast and provide long term water security for the future. The plan also includes drought management measures to ensure we are prepared to respond to droughts in the future.
How can I have my say on the draft plan?
The Central Coast Water Security Plan was placed on public exhibition from 31 August until 12 October.
During this time, we encouraged the community to visit Your Voice Our Coast – which is Council’s online engagement hub – where they were able to review the plan and supporting factsheets before providing their final feedback using our online submission form.
We are now reviewing the feedback we received on the plan before finalising the plan later in the year and submitting the plan to the Department of Planning, Industry and Environment for their review and approval.
Who has been involved in developing the plan?
Central Coast Council has worked closely with Hunter Water Corporation, the NSW Government – Department of Planning, Industry and Environment (Water), industry experts, and the Central Coast community to ensure the plan reflects our community values, is adaptive, resilient to change and in line with best water management guidelines.
…but the drought is over, and we seem to have lots of water, why do we need to change anything?
Our community told us that the top three values when it came to water supply options were:
- environmental sensitivity
- financial efficiency.
Central Coast Council have traditionally relied upon surface water (dams) and rainfall to store and supply water to our community and while the system performs well in average climate conditions, we are vulnerable to drought.
As seen in previous droughts, including the millennium drought, rainfall can be low and evaporation rates can be high in our dams and catchments, which leads to depletion of water supplies relatively quickly. Our catchment streams and rivers slowdown in flows, which means we are unable to harvest as much water into our dams.
The Central Coast water storage can fall from typical operating levels to critical levels in around 5-6 years in a severe drought, even with a range of drought response measures in place to slow the rate of depletion. If a severe drought was to continue beyond this, the water supply system could fail, and the Central Coast could run out of drinking water. Although the probability of this happening is very low, the consequences for the Coast would be catastrophic.
We know our climate is changing, but we are also learning about climate variability. New modelling methods and datasets show our water supplies may be less secure than we previously thought. We now understand that there have been droughts far longer and more severe than those observed during the last 120 years. We also learnt through the recent drought that we need to be prepared for drought before the next drought.
The Central Coast population continues to grow, and we need to secure supplies for a growing population now and into the future.
How have we considered climate change?
The NSW Government has invested in new modelling methods and datasets to develop a better understanding of both historical climate variability and likely future climate conditions. This modelling shows our water supplies may be less secure than we previously thought. We now understand that there have been droughts far longer and more severe than those observed during the last 120 years.
Data reconstructed from before instrumental records began, using sources such as tree rings, cave deposits and coral growth (referred to collectively as paleoclimate data), also indicates that we could see higher temperatures and less rainfall in the future.
We tested the potential impacts of climate change on the supply and demand for water in future and our preferred portfolio can adapt to the current predicted impacts of climate change.
Will any of the actions reduce our drinking water quality?
No. The actions proposed in the plan will ensure drinking water continues to meet strict water quality requirements in line with the Australian Drinking Water Guidelines.
Given Council’s financial situation, how will the actions be funded?
Council’s preferred portfolio of supply options represents the lowest cost approach to meet the future water needs of our growing community. By maximising the efficient conservation of water and optimising the capability of our existing supplies, investments in the construction of new supply sources can be deferred.
Future new water supply sources (purified recycled water and desalination) would be funded through a combination of developer charges, available government grants and Council’s water business revenue (i.e. future pricing proposals to IPART for water, sewer and stormwater services).
Drought readiness actions and investigations to manage risks identified with Council’s preferred supply portfolio will be funded through revenue sought as part of Council’s next IPART water, sewer and stormwater pricing determination.
How does this plan relate to our submission to IPART for water, sewer and stormwater pricing?
The Independent Pricing and Regulatory Tribunal (IPART) sets the prices for the water, sewer and stormwater services provided by Central Coast Council.
In 2018, IPART set Council’s prices for water, sewer and stormwater services for a three-year period, from 1 July 2019 to 30 June 2022, following a pricing submission made by Council. Typically, a pricing determination goes for four years, however IPART set it for a three-year period due to the newly merged Council.
Council submitted their next pricing proposal to IPART on 10 September 2021, and IPART will determine what prices Council can charge for these services from 1 July 2022 until 30 June 2026.
Council's pricing proposal outlined proposed service levels and prices for water, sewer and stormwater. It is a proposal only, and IPART will test the proposal and make any changes they deem appropriate. IPART are currently consulting with the community on our pricing proposal and their Issues Paper.
The only aspects of the draft Central Coast Water Security Plan that was included in our pricing proposal to IPART for our water, sewer and stormwater pricing (2022-2026) is to seek revenue for the drought readiness actions and investigations to manage risks, identified with Council’s preferred supply portfolio.
Future new water supply sources (purified recycled water and desalination) would be funded through a combination of developer charges, available government grants and Council’s water business revenue (i.e. future pricing proposals to IPART for water, sewer and stormwater services).
How does this plan fit into the independent review taking place of Council’s water and sewer operations?
Central Coast Council is unique in New South Wales in being the only Council owned water authority alongside the State-owned Sydney Water and Hunter Water.
Council has commissioned an independent review of the model governing its water and sewer operations.
Regardless of how our water and sewer assets and services are governed, the Central Coast Water Security Plan, as our long-term water plan, will be implemented – after it is finalised (post-public exhibition), approved by the Department of Industry, Planning and Environment and adopted by Central Coast Council.
For more information on what this review entails, read the media release.
How have the community been involved?
Over the past year we have undertaken an extensive community engagement to understand the values, views and preferences of the Central Coast community and to inform the decision making for the Central Coast Water Security Plan. This included a three-phase consultation program with qualitive and quantitative communication and engagement tools and techniques to provide opportunities for community input and feedback on the plan.
The consultation we undertook was with a representative group of the community, and happened in three phases: last year in December and then this year in February and April – using deliberative forums and in-depth phone interviews for those who couldn’t attend in an online setting.
As these forums and in-depth phone interviews were of a representative sample of the Central Coast’s demographic, the data we received from these was used to inform the development of our water security plan.
During the second and third phases of community consultation, we also ran two online opt-in surveys – one in February and the other in April – these both were open to the community at the same time as forums two and three. However, these surveys were available to anyone to fill in, so the data we received from these surveys was not representative of the Central Coast. As such, these surveys were used to build awareness within the community and identify areas where future engagement and education would be of most value. This dataset did not directly inform the development and selection of the preferred portfolio within the CCWSP.
This plan is the culmination of community engagement, liaison with key government agencies and industry, and expert technical studies and recommendations.
Community feedback is currently being collated and the plan will be finalised and provided to Council and the NSW Department of Industry and Environment for approval.
The community are invited to check out our:
- engagement snapshot: a two-page snapshot on how we consulted with the community and the top results
- engagement summary: a ten-page summary on how we consulted with the community, and more in-depth results
- consultation report: over 200 pages outlining what we did, what we heard, our response and the next steps of this project
What were the community’s priorities for the plan?
Through the community consultation process of the Central Coast Water Security Plan we heard that our community wants:
- a safe and reliable water supply that can withstand drought
- investments to minimise the environmental impacts of water supply initiatives
- investments that are cost effective
- consideration of strengthening Water Wise Rules and water restrictions to make the most of our water resources
- investments in community education and empowerment
- investments in water recycling and conservation.
How has the community helped shape the plan?
Understanding our community’s values and preferences has been a key focus of developing the Central Coast Water Security Plan. We have considered these values and preferences in the decision-making process alongside robust analysis of a range of policy, planning and infrastructure options.
Community values align with the goals and objectives of the Central Coast Water Security Plan and have informed the strategic priorities and decision-making criteria. Community preferences across a range of supply and demand options were used to inform the development of a range of portfolios considered in the development of the plan.
Actions in the plan
What sort of actions are included in the plan?
The plan proposes a diverse range of infrastructure, research, policy and evaluation actions including:
- reducing the amount of water we use through water efficiency and conservation activities
- improving utilisation of our existing infrastructure to enhance supply
- increasing the supply of climate independent water sources to meet future demand
- planning for drought response and increased climate variability
- continuing to protect drinking water catchments
- improving broader social and cultural outcomes.
Is any major infrastructure proposed to be built?
The first two pillars of the plan seek to make the most of existing water sources and infrastructure before any major new infrastructure is required.
The third pillar of the plan would then introduce new climate independent supplies for an adaptive future. This includes the construction of an advanced water treatment plant at Wyong South Wastewater Treatment Plant to produce purified recycled water.
The plan also proposes to construct a desalination plant at Toukley as a permanent water supply source. These major investments would be triggered in response to significant population growth or future severe droughts.
Why can’t we just save more water through water conservation and recycling more?
In line with our community’s preferences, the Central Coast Water Security Plan includes ongoing investment in water conservation, reducing leaks throughout our water system and increased utilisation of recycled water schemes to make the most of our existing resources.
However, these programs alone are not enough to meet our community’s expectation for a reliable water supply that can withstand drought.
We also need to increase the supply of water so that we can meet our community’s minimum water needs in drought and prepare us for a future with a growing population and an uncertain climate.
How did you decide what to include in the program of actions?
Council took an ‘all options on the table’ approach and identified a broad range of potential actions which were assessed through several criteria to shortlist the actions and combine as appropriate into portfolios of options.
Extensive financial analysis, along with an assessment of social and environmental factors and consideration of community values and preferences, were used to select the proposed program of actions. This was undertaken in line with the Department of Planning, Industry and Environment’s guidelines on Integrated Water Cycle Management.
The decision-making framework identified that there is no need to trade-off between community, financial and technical drivers for Council’s preferred portfolio.
What are the main actions of the Central Coast Water Security Plan?
There are three key pillars outlined in the draft plan and a suite of actions that align with each pillar. These actions will be implemented once the final plan is adopted.
Pillar 1 - Conserve and use water efficiently
We will manage our existing water resources wisely and work together with our community to do the same.
Since the millennium drought the Central Coast community has reduced their water use within their homes by 22% and in the last year Council has inspected over 1,200 kilometres of water pipes in our network to identify and fix leaks in the system.
We will continue to build on these achievements and work with our community to reduce drinking water used in homes, businesses and industries and continue to invest in reducing leaks in the water network.
Pillar 2 -Maximise existing water supplied so we can delay new water supplies
We want to make the most of our existing infrastructure.
We will continue to capture and store water in Mangrove Creek Dam, which can store water transferred from Mardi dam which in turn captures water from Wyong river and Ourimbah creek.
Following a comprehensive safety review, Mangrove Creek Dam can now be utilised to its full storage capacity.
We will also continue our partnership with Hunter Water and maximise on the water transferred from the Central Coast-Hunter connection to increase water security across the two regions.
Groundwater borefields and infrastructure was built during the millennium drought and has been used as a water source on the Coast. We are planning to reinstate our groundwater system and conduct further studies to ensure that any groundwater extraction is undertaken in the most sustainable way. We will also continue to investigate a potential ancient underground river source (also known as a paleochannel) under the Tuggerah Lakes area, which could provide even more water.
We currently recycle around 650 million litres of water each year. We will work towards increasing this by 400 million litres per year through increased industrial recycling, providing recycled water to irrigate more parks and sporting fields, and continuing to explore viable recycling opportunities in new residential developments.
Pillar 3 – Develop new supplies of water, independent of rainfall for an adaptive future
Our climate is changing, and the future is uncertain. We will act to improve our resilience to drought and remain adaptive to future opportunities and risk. We will do this by implementing the following actions.
Purified recycled water is a reliable and safe water supply option that is already part of water supply systems around the world, including Perth Western Australia. While we plan for the delivery of a purified recycled water scheme at Wyong South Wastewater Treatment Plant. Council will continue to engage with our community on the water cycle and the potential future option of purified recycled water for drinking.
Council is also planning to build a desalination plant at Toukley as a long-term supply option to provide a reliable source of water that is independent of rainfall and climate. Desalination is the process of removing salts and impurities from seawater to create safe drinking water.
The desalination plant would be sized to produce up to 30 million litres of water per day in typical conditions and even throughout a drought.
What are the options within the preferred portfolio?
Below is a graphic of the preferred portfolio summary in the order of proposed implementation:
Catchment management and protection
What is catchment management?
A catchment is an area where water is collected by the natural landscape. We use the water collected from our catchments to help supply water for our needs, by building dams and weirs, or tapping into groundwater.
Human activities affect the health of our water catchments and the volume and quality of water from these areas. Catchment management involves working with local councils, landholders, government agencies and industry so that everyday activities in the catchment do not harm the environment that our drinking water comes from.
What is Council doing about catchment management on the Central Coast?
Council has prepared the Central Coast Local Environmental Plan (LEP) and associated Development Control Plans to replace the former Council’s planning requirements. These documents contain requirements for developments occurring within drinking water catchments. This includes the submission of Water Quality Management Plans to ensure that any development has a neutral or beneficial impact on the drinking water supply.
Central Coast Council currently undertakes catchment management across four key areas through strategic planning, dedicated management and monitoring programs, land management and compliance activities.
We will continue to work collaboratively with landholders and government agencies to balance the development needs of a growing region with the provision of healthy water catchments that will deliver high quality water. We are not proposing any changes to Central Coast’s provisions in the legislation.
What are the benefits of catchment management?
Looking after our catchments is the first step in protecting our drinking water supply. It also provides broader environmental and social benefits through improved catchment and waterway health.
We’re making the most of our existing water resources so we’re only investing in new water sources when they are needed.
What is a multiple-barrier approach?
Managing drinking water quality begins at the start of the water cycle – whether that is in the catchment the moment rain falls for our dams, or in the ocean for a desalination plant – right through to consumers turning on their taps.
At each stage of the water collection, storage, treatment and delivery processes there are opportunities to manage water quality. This is called the multi-barrier approach – where water quality risks can be prevented or managed at multiple points of the process, not just relying on a single barrier in the supply system.
How does Council ensure safe and clean drinking water?
Council is committed to providing high quality drinking water for all residents. Regular tests are performed by Council and independent registered laboratories to ensure our water is safe for human consumption and complies with the water quality guideline values provided in the Australian Drinking Water Guidelines.
Click here for further information on drinking water quality and management.
What is water conservation?
Water conservation is the practice of using less water, or using it more efficiently, to reduce water usage.
Water conservation programs aim to reduce the demand on drinking water supplies by:
- encouraging the community to use water more efficiently.
- identifying and repairing leaks in Council owned and privately-owned water systems
What water conservation measures are in place now?
We have worked with the Central Coast community and businesses to reduce the amount of water we use. Some of the notable resources that we have developed include:
- reducing leaks using leak detection programs, monitoring the system and reducing response times to reported leaks
- our Love Water website
- an online water supply game: Working with Water
- educational resources for primary and high school classes
- repair and maintenance guides
- a 360 virtual tour of two storage dams on the Central Coast
- a small business water education program
- a Central Coast water supply system animation
- an optional installation of free smart water data loggers for two months – where Council can monitor the school’s water usage
- Dr. Hydro Incursion at early childhood centres
- water education packs at 130+ early childhood centres.
What actions are proposed in the Central Coast Water Security Plan for water conservation?
As part of the Central Coast Water Security Plan, we will develop a water conservation strategy – aligned with the New South Wales Water Efficiency Framework and Program. The key components of our Water Efficiency Plan will include:
- a focus on gaining a better understanding of the main drivers for water efficiency on the Central Coast, including future demand and supply analysis, climate change and population impacts on water usage
- community engagement and education to promote water efficient behaviours and uptake and maintenance of water efficient devices
- research and development into emerging water saving technologies, designs and identification of water efficiency options
- implementation of the Economic Level of Water Conservation (ELWC) tool for assessing water conservation options, taking into the account the need for a wholistic approach to evaluating water savings programs
- design and assess water efficiency pilot programs
- continued improvement of active leak detection and water management programs, through water audits, smart meters and data logger installations
- collaboration, where possible, with Hunter Water Corporation and the Department of Planning Industry and Environment in developing parallel water efficiency tools and programs.
What are the benefits of water conservation?
Water conservation is crucial to managing the current and future supply and demand balance by doing more with less. Benefits include deferral of major investments, reducing the amount of water extracted from the environment for consumption and reducing the amount of water that is treated and pumped around the system.
How reliable are water conservation measures at reducing demand on our water supply?
Water conservation programs rely on water efficient behaviours and the adoption of water efficient appliances across the community. The effectiveness of water conservation programs can be difficult to measure because demand for water is heavily influenced by weather which can often mask changes in consumption.
Has Council considered rainwater tanks for residential properties?
Development application and BASIX policies for new dwellings require rainwater tanks be installed to encourage stormwater reuse – these are typically connected to the internal plumbing of the dwelling for toilet flushing and laundry washing, as well as outdoor uses. Council has developed a rainwater tank maintenance guide to ensure residents are catching water effectively, and maintain its quality.
A Council subsidised rainwater tank scheme was one of the options assessed and considered as part of the development of the Central Coast Water Security Plan. However, the results indicated that this option was the most inefficient of all the shortlisted options on a cost per yield ($/kL) basis. Other issues identified with rainwater tanks are that due to the tanks being owned and maintained by customers, there is no guarantee that they will continue to be maintained or operated effectively over the long term. Studies by other New South Wales Water Authorities have identified ongoing reliability issues and hesitancy for future pump replacements which impact on long term demand reduction.
What about larger scale stormwater harvesting?
There are three existing Council-owned stormwater harvesting sites (Central Coast Stadium, Hylton Moore Park and Terrigal Reuse scheme) as well as several privately owned stormwater harvesting sites on the Central Coast.
As part of implementing the Central Coast Water Security Plan we will be investigating the potential of these existing stormwater harvesting assets to further offset demand on the drinking water supply. We will also investigate opportunities to better facilitate stormwater harvesting potential when new communities are being planned.
How much water do we currently recycle?
Central Coast Council’s recycled water schemes currently produce a total of around 1.81 megalitres per day at the following sites for internal operations as well as the watering of nearby parks and sporting fields:
- Bateau Bay Wastewater Treatment Plant (WWTP)
- Toukley WWTP (including Magenta Shores)
- Kincumber WWTP
- Mannering Park WWTP
- Central Coast Stadium Reuse Scheme (Graham Park)
- Hylton Moore Park Reuse Scheme
- Terrigal Reuse Scheme
How is water recycled?
Recycled water involves the treatment of wastewater (sewage) or stormwater to a standard suitable for a variety of uses, such as industrial and commercial uses, toilet flushing or irrigation of parks, gardens, crops and golf courses. The process relies on advanced water treatment, such as UV disinfection or chlorination. Water sourced for recycling projects is treated according to the Australian Guidelines for Water Recycling, which means it is safe for its intended use.
What actions are proposed in the Central Coast Water Security Plan for recycled water?
Council’s recycled water and stormwater harvesting schemes are in various states of operability following their installation in response to the millennium drought. A key focus of the Central Coast Water Security Plan is to further investigate and undertake the refurbishment and upgrade of the existing plants where it is effective to do so. We will also undertake community engagement, to better understand the needs of our existing customers to encourage greater usage, while also identifying the potential for new customers.
What are the benefits of recycled water?
Recycled water schemes reduce demand on our drinking water supplies. It is a reliable and alternative source of water that doesn’t rely on rainfall and:
- provides an alternate source of water for non-drinking water purposes
- supports liveable communities by irrigating parks and sporting field
- helps delay the need for major water supply augmentations in the future.
Using recycled water delivers environmental benefits by reducing the volume of treated effluent discharged to the ocean.
Why don’t we recycle all our wastewater?
Recycling water schemes rely on end uses such as industry or parklands to be located close to existing treatment infrastructure. Costs involved in constructing additional storage, treatment and reticulation infrastructure can be relatively high compared to other options, particularly for schemes that produce relatively small volumes of water. Our plan is to maximise the use of recycled water where it is most efficient to do so.
Is recycled water safe?
Recycled water is treated and monitored according to the Australian Guidelines for Water Recycling, which means it is safe for its intended use.
Purified recycled water for drinking
What is purified recycled water?
Purified recycled water is high-grade, ultra-clean water produced by taking treated wastewater or stormwater, and treating it further through advanced treatment processes, to filter and purify it before adding it to an existing water source, such as dams or aquifers (groundwater). Water is treated again when extracted from the water source to ensure it meets Australian Drinking Water Guidelines and is safe to drink.
Is it the same as other recycled water?
No, purified recycled water begins with recycled water and puts it through further treatment steps, to make it high-quality, safe drinking water.
Does the plan consider adding purified recycled water to our drinking water supply?
Yes, the plan proposes actions to develop a purified recycled water scheme associated with the Wyong South Wastewater Treatment Plant (WSWWTP). A new advanced water treatment plant would be constructed at WSWWTP and transfer purified recycled water to the Wyong River, upstream of the water supply weir. The water would be mixed with existing river flows before being extracted for storage at Mardi Dam.
The plan proposes further engagement with our community and stakeholders about this option, in conjunction with Hunter Water Corporation, to help the community understand the water cycle and the potential role purified recycled water could play in both regions’ water futures.
Do any other cities use purified recycled water?
Yes, purified recycled water is now part of the water supply mix in over 35 cities around the world, especially in America.
Across Australia, Perth already has an active groundwater replenishment scheme using recycled wastewater; Orange, NSW has an active stormwater recycling scheme; and Seqwater’s drought response plan includes turning on the Western Corridor scheme if their dams drop to 40%.
Why are we considering purified recycled water for drinking?
All water is recycled as part of the natural water cycle. Informal recycling happens all around the world wherever upstream towns discharge wastewater to rivers that is treated and used by downstream towns for drinking water.
Purified recycled water for drinking is a safe and reliable water supply option that offers several benefits as a potential future water supply option for the region.
What are the benefits of purified recycled water?
Purified recycled water for drinking is a safe and reliable, rainfall-independent source of water and is often lower in cost and more energy efficient than other rainfall-independent options like desalination. It is also an environmentally friendly option that reduces the water taken from the environment and also reduces nutrient discharges to waterways associated with effluent discharges from our wastewater treatment plants.
Is purified recycled water safe to drink?
Yes, purified recycled water is safe to drink. Like the rest of our water supply system, any new purified recycled water scheme would be subject to strict treatment, monitoring and regulation.
Water is treated through several stages. Each stage uses a specific technology or control point which play a specific role to manage any impurities in the water. This is referred to as a multi-barrier approach.
Any potential scheme would be developed in close consultation with health authorities and experts and meet the Australian Guidelines for Water Recycling as well as the Australian Drinking Water Guidelines.
Interregional water sharing
What is water sharing?
Water sharing involves moving water across regions to where it is needed most through a network of pipes and pumps. Agreements determine when and where water transfers.
Do we currently have water sharing with other regions?
Yes. Central Coast Council and Hunter Water Corporation have an existing pipeline connecting the two regions. The pipeline can transfer water in either direction according to established water sharing rules.
What actions are there in the Central Coast Water Security Plan for water sharing?
We will continue the existing water sharing arrangements with the Hunter Water and enhance them where possible to ensure both regions are best placed to respond to drought, operational needs, meet future growth requirements and adapt to climate change.
What are the benefits of water sharing?
Water sharing allows water to be transferred to where it is needed most. It optimises existing infrastructure to take advantage of variations in rainfall distribution and storage capacities across the two regions.
What is desalination?
Desalination is the process of removing salts from saline or brackish water to create freshwater suitable for drinking. A process called reverse osmosis is commonly used, where the saltwater is pushed through a membrane (a barrier with tiny holes) to remove the salt and mineral content. The size of a desalination plant can range from a small unit, the size of a shipping container, to large plants which can provide hundreds of millions of litres of water a day.
Desalination is an important climate-independent water supply option and was originally identified in the Central Coast Council’s WaterPlan 2050 as a drought response measure and potential long-term supply source.
How do we use desalination currently?
We don’t have a desalination plant in the Central Coast region. Development consent for a 20 million litre per day drought response plant was previously obtained from the State Government and activated in response to the millennium drought. Subsequent recovery of the region’s water storages allowed Council to defer the construction of the plant.
What actions are there in the Central Coast Water Security Plan for desalination?
The Toukley drought response desalination plant is also being considered as a long-term supply option. This site was shortlisted based on a range of criteria, including site availability, proximity to Council’s water distribution network, power supply, access to seawater for raw water intake and brine discharge, and potential environmental and social impacts. The proposed intake structure type is being changed from a collection structure initially proposed under the dunes at Budgewoi Beach to a conventional direct ocean intake structure located off the coast between Noraville and Magenta.
The most appropriate size of the desalination plant being considered is between 20 to 30 million litres per day as both a long-term supply option, and a drought response measure.
As noted above, a concept design and development consent has previously been obtained for a desalination plant at Toukley capable of producing up to 20 million litres of water per day as a drought response measure. Council will be seeking to prepare a revised concept design and amend the existing development consent to allow for the alternate intake structure location and provide greater flexibility in scale for the plant.
What are the benefits of desalination?
A permanent desalination plant at Toukley would add a new climate-independent water source to the Central Coast water supply system. This would provide a very reliable source of supply that is not dependant on future rainfall.
The plant improves the diversity of the water supply system and the resilience of the system to respond to shocks including drought, water quality issues in our catchments (including algae) and other major asset outages.
What is the difference between a drought response desalination plant and a long-term water supply desalination plant?
There is little difference for the Central Coast as the preferred location, scale and technology is the same. While we forecast when long-term supply measures would need to be implemented due to growth in demand, we also recognise a severe drought could trigger the construction of desalination earlier to mange the risk of running out of water.
The design of any desalination plant would ensure that the asset could be integrated into Council’s broader water supply network for future usage when dam levels drop in the future. During times of high dam levels, the plant would not need to run, with the plant then operated when storage levels drop or in response to operational issues at other treatment facilities. This would be similar to the operation of the Sydney desalination plant.
What are the social and environmental impacts of a desalination plant?
The previous Statement of Environmental Effects (SEE) determined that the 20 ML/day Toukley Desalination Plant would only result in minor impacts to the environment. The Toukley scheme benefits from the ability to dilute the brine waste stream within the existing Norah Head Ocean Outfall (wastewater effluent). Additional environmental and social impact assessments will be undertaken as part of the revised concept design required to amend the proposed intake structure and provide flexibility in scale of the plant.
This includes various marine studies and land-based environmental assessments, which together will form part of the updated Environmental Impact Statement (EIS) documentation. In line with our community’s preference for an environmentally sustainable water supply system, we have also included carbon offsetting to reduce the environmental footprint of the desalination plant’s energy consumption.
How is the brine and biproducts of desalination managed?
Brine and other liquid stream by-products would be disposed of via the existing Toukley sewerage scheme ocean outfall which transfers effluent from five wastewater treatment plants to the ocean. This would be in line with the required environmental impact assessments and ongoing monitoring to avoid adverse impacts to the environment. This had been assessed and approved by the state government previously for the Council’s potential Toukley 20ML/day drought response desalination scheme.
What will the desalination plant project cost to build and operate?
The estimated total cost of construction for the 30 ML/day desalination plant is $230.1M and cost to operate is approximately $16.1M.
The estimated total cost of construction for the 20/ML day desalination plant is $205.7M and cost to operate is approximately $11.6M.
Did Council and Hunter Water Corporation consider a joint desalination plant?
The likely timing for Hunter Water’s Belmont desalination plant and desalination required to manage our long-term supply and demand balance do not align. There are also constraints that would prevent significant upscaling of the planned capacity of the Belmont plant to meet Council’s future requirements.
However, there would be future opportunity for considering joint investment as part of Hunter Water’s future drought response desalination scheme at Walsh Point. This site would provide more opportunities to increase scale to better meet the needs for both regions.
What is groundwater?
Groundwater is one of the most common water sources used throughout the world. Groundwater can be found in fractured rock or layers of sand and gravel called aquifers. Aquifers provide natural underground reservoirs that can offer a reliable supply of water, even in times of drought.
Water is pumped out of the ground through wells and treated to drinking water supply. All naturally occurring groundwater originally came from rainfall, though this may have occurred a very long time ago.
How do we use groundwater currently?
Council’s three main borefields at Woy Woy, Ourimbah (Bangalow) and Mangrove Creek, were commissioned during the millennium drought as Council searched for new water supply sources. However, since the end of the millennium drought, these bores have been out of operation or decommissioned due to the availability of other surface water sources.
These supplies have only been operated as a drought contingency to minimise operational costs. Additional investment is required before the schemes can be used in a more optimised way.
What actions are there in the Central Coast Water Security Plan for groundwater?
There is potential to increase groundwater extraction from existing systems over the longer term, to allow us to defer the construction of new sources of water. This would occur within existing extraction rules that are regulated by the NSW Government to ensure sustainable use of this supply source.
Palaeochannels are water bearing sands and gravels associated with ancient river systems. Council has identified potential palaeochannels on the Central Coast, which may provide alternate and additional water supply in the future.
The extent and connectedness of the palaeochannels, and any potential pathways from the surface are still unknown. The next phase of investigations would be to install exploratory bores to further investigate these sources and better understand their geology and water quality parameters.
We will continue to investigate this option, as well as aquifer storage and recovery, as potential future resources. Council is also investigating sustainable methods to further increase the utilisation of its existing groundwater sources.
What are the benefits of groundwater?
Groundwater is generally a low-cost water supply option with moderate social and environmental impacts. Previous investments made following the millennium drought can be leveraged to provide additional long-term supplies without the need for significant investment.
The palaeochannel may provide freshwater to add to our supply system or, alternatively, provide an additional underground water storage which could be replenished during times of significant rainfall for use during drought.
Has Council considered the environmental impacts of groundwater extraction?
Existing government regulations are in place to ensure that Council extracts groundwater in a sustainable manner. The extraction of groundwater by Council is governed by licence conditions and water sharing plans regulated Department of Planning Industry and Environment (DPIE).
Regular environmental monitoring is undertaken to assess potential impacts of groundwater extraction on the aquifers and environment, including Groundwater Dependent Ecosystems (GDE’s). The protection of GDE’s is also covered under the relevant Water Sharing Plans for the Central Coast hard rock, alluvial and coastal aquifers which Council must comply with.
Further environmental and hydrogeological investigations will be undertaken at existing and potential groundwater extraction locations to confirm the yield potential of the aquifers as well as any environmental impacts of increased extraction.
How much groundwater supplies will contribute to the severe drought scenario?
Groundwater supply sources on the Central Coast are recharged depending upon the aquifer characteristics and rainfall in the region. During prolonged drought the supply from groundwater sources may be impacted. Council assumes a significantly reduced groundwater yield when planning emergency drought supplies. Further investigations will be undertaken to determine the potential contribution of groundwater supplies during drought.
How are we using our dams now?
Mangrove Creek Dam
Mangrove Creek Dam was built due to a rising demand for water from an expanding population. The dam was built to boost water supply storage for the Central Coast and to help provide a more reliable water supply.
Mangrove Creek Dam offered several advantages as a site for the region’s major dam. The dam site was determined by the NSW Department of Public Works in the 1970’s after extensive investigation. The decision was based on several environmental, physical and financial considerations including:
- dam size: For a dam this size the site is the closest possible location to the coastal areas where most people live
- catchment: The land comprises extensive undeveloped, uninhabited land which helps to maintain a pristine catchment area
- geology: The site has a rock foundation. Areas with a sandy base are not suitable for dam construction. The naturally V-shaped valley is the ideal storage with a small surface area compared to volume – which means less surface evaporation
- future water supply works: The dam site is located relatively close to all other water catchments – which minimises the costs associated with transfer pipelines and pumping stations
Mangrove Creek Dam was proposed as a large storage dam, not primarily a collection dam. Its catchment area was relatively small, but the shape of the valley and its geology enabled the construction of an 80-metre-high wall that would store 190,000 million litres of water.
Located 4km south-west of Wyong, Mardi Dam was built in 1962. Mardi Dam is an off-stream storage facility, meaning it is not fed directly by a stream and must be filled by pumping water from Wyong River and Ourimbah Creek. Water is pumped to Mardi Treatment Plant and then to residents.
Mooney Mooney Dam
Built in 1961, Mooney Mooney Dam is the region’s oldest dam and is 10km north-west of Gosford. Water is pumped to Somersby Treatment Plant and then to residents.
Are any new dams proposed?
No. Following a rigorous short-listing process, we investigated the feasibility of a potential new dam at Toobys Creek. We also investigated raising Mangrove Creek Dam. However, these options were not favoured based on financial, social and environment impact assessment, and were less favoured by our community as a future water supply option for our region.
Are we making the best use of our existing dams?
We optimise the operation of our existing dams given streamflow, reliability and environmental protection requirements.
We also benefit from storages in the Hunter Region through an interconnecting pipeline that links the Central Coast Council to the Hunter Water System.
Following a comprehensive safety review, Mangrove Creek Dam can now be utilised to its full storage capacity. We will continue existing water sharing arrangements and enhance them where possible to ensure both regions are making the best use of all our dams.
Your questions answered...
How is this plan taking into consideration all the housing development occurring in Central Coast areas?
Council uses a consultant (.id- Informed Decisions - https://forecast.id.com.au/), to forecast population growth. The forecasted population is used to the forecast housing development (single and multi premises) which is used in demand forecasting tool to determine future water demand for central coast.
For more information on population and water demand forecasting, please see our factsheet.
I live at Umina pump ground water for my garden. I have a licence from the NSW Government allowing me to pump a defined volume 'IN PERPETUITY'. What impact will the plan have on my established water rights?
Central Coast Council has an existing licence to extract and treat groundwater from the shallow aquifer at Woy Woy Peninsula. As part of the Central Coast Security Plan, Council proposes to utilise the existing groundwater allocation and investigate the potential to increase extraction of water within the current limits set in place and regulated by the Department of Planning, Industry and Environment.
I'm wondering why the Central Coast's water supply smells and tastes so heavily of chlorine? What is the reason for this being added? Is this a risk to the community by drinking this daily? Have there been studies to show the effects of this?
All Australian water utilities must disinfect water supplied to customers to prevent the spread of waterborne diseases. This is achieved by the addition of chlorine at the treatment stage, and at key locations throughout the distribution network. The Australian Drinking Water Guidelines specify the concentration of chlorine to be maintained to prevent the growth of waterborne pathogens and to ensure that the water is safe for consumers to drink. Council routinely tests the concentration of chlorine in its network to ensure that it remains in the range specified in the guidelines.
Customers may notice a chlorine taste or odour if they live close to a point of chlorine dosing. Seasonal changes in demand and temperature may also change the amount of chlorine present in the water at any given point. The taste and smell of chlorine can be eliminated by placing some water in a covered jug in the refrigerator. It is recommended this water be consumed within 24 hours. Domestic water filters or jug filters are also useful to reduce the chlorine present in the water consumed.
If you would like further information on the use of chlorine to disinfect drinking water, please refer to the Australian Drinking Water Guidelines.
If you have any concerns about your water quality, or suspect that the chlorine residual is too high at your residence, please call Council on 1300 463 954 so that we can arrange an investigation.
I understand that the Mangrove Creek has never been filled to more than about 75% capacity. How is enlarging the dam ever going to add to this with the same catchment?
Historically the ability to fill Mangrove Creek Dam was limited to relying on inflow from its natural catchment. The “missing link” between Mardi Dam and Mangrove Creek Dam was installed in 2012 which now allows the dam to be filled from pumped transfers from the larger combined catchments of the Wyong River and Ourimbah Creek. Council has also recently resolved a capacity constraint associated with the dam’s spillway that prevented filling beyond 80% (and pumped inflow beyond 75%).
These measures now allow the dam to operate to its full potential and raising the dam was one of many options considered under the Central Coast Water Security Plan. However, the options that require the raising of Mangrove Creek Dam are not included in the preferred supply portfolio as outlined in the Plan.
For more information relating to Council’s existing water supply scheme, including brochures and a video, can be found at Council’s Love Water website.
Why would this decision be beneficial to the community considering we have covid in our sewers, what's to say this virus won't travel in other waterways?
Purified recycled water (PRW) for drinking is a rainfall independent supply of water and is therefore a reliable and resilient water supply source for the community in drought and non-drought conditions. It also provides environmental benefits by reducing the volume of treated wastewater released to waterways.
All water is recycled in nature as part of the natural water cycle. Technology now allows us to speed up this process to provide clean and safe drinking water. In many places around the world, including Perth in Western Australia, water is recycled by purifying or treating wastewater to a level that makes it safe and suitable to go back into the drinking water supply. This is referred to as purified recycled water (PRW) and is subject to multiple stages of treatment and monitoring. The wastewater is treated at an existing plant before it then goes through a highly refined treatment process at a new, more advanced water treatment plant. This purifies the water by removing any microbes or extremely small particles, such as viruses and chemicals, in a similar process to desalination and includes advanced disinfection processes.
We’re investigating a PRW scheme that involves sending highly treated recycled water to mix with water extracted from Wyong River, and stored in Mardi Dam. The water would then be treated again at the existing Mardi Water treatment plant, then supplied to Central Coast customers.
The Central Coast drinking water supply has three treatment plants that treat and deliver quality water complying with the Australian Drinking Water Guidelines. Studies on viruses including other coronaviruses, suggest that the structure of the COVID-19 virus is more sensitive to disinfection than many other viruses. These disinfection methods include oxidation (chlorine, monochloramine and chlorine dioxide) as well as inactivation through the use of ultraviolet irradiation (UV) and ozone. There is also preliminary research which suggests that primary grit chamber screening and activated sludge treatments can also aid in removing or degrading COVID-19 RNA. In addition, detergents and other chemicals in sewage can inactivate the COVID-19 RNA before it reaches the sewage treatment plant.
Council will need to establish that the selected treatment train to be used for PRW, will remove all potentially harmful viruses including COVID-19, with ongoing operational monitoring and data reviews to ensure the water is safe to drink and safe for the environment.
The Water Services Association of Australia state that there is no evidence that the coronavirus causing COVID-19 has been transmitted via wastewater systems – including before and after treatment. Wastewater continues to be managed and treated properly and carefully by water utilities to protect public health and the environment. For further information regarding COVID19 in water and wastewater as well as Council’s drinking water treatment process please refer to the links below:
- Water Services Association of Australia – Fact Sheet: COVID-19 and Wastewater
- Water Services Association of Australia – Fact Sheet: COVID-19
- Global Water Research Coalition – COVID-19 Virus: Water, Sanitation & Wastewater Management
- World Health Organization – Water, sanitation, hygiene and waste management for SARS-CoV-2, the virus that causes COVID-19
- Water Research Australia: COVID-19: The What and Why of Sewage Surveillance
- Central Coast Council – Water Treatment Process