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What is water banking?

It involves storing water underground using managed aquifer recharge (MAR) techniques.

Excess water resources are stored when available and allocated for future use during dry years or a drought.

This water is managed within an entitlement framework to meet competing demands.

Water can be sourced from rainwater, rivers, dam releases or alternative sources, such as recycled wastewater and urban stormwater.

We all need water. But rapid population growth and changes in climate may mean we have to do more with less. 

Or… we could tap into some of the water around us that we just don’t use: excess surface water, treated wastewater, and urban stormwater.

Of course if we save this water we need somewhere to bank it (for a not so rainy day).

Rather than giant, unsightly, above-ground storage tanks, we can use large naturally occurring underground reservoirs called aquifers. They hold water in porous or fractured rock or loose, unconsolidated sediment. Less permeable layers -like clay- help to contain the stored water.

The CSIRO focuses its research on how best to use aquifers to store, convey and treat water. 

Storing water like this is known as Managed aquifer recharge.

Most agricultural areas have a wet season, so let’s start there.

There’s high rainfall and less demand for irrigation. In other words a perfect time to capture excess runoff. Water is simply filtered through the soil and “banked” in a shallow aquifer. It’s then ready as an economic irrigation supply when the dry season returns. 

And as a bonus, storing water this way means no algal blooms, no mosquito problems and reduces the water lost to evaporation when things inevitably heat up and dry off.

In urban settings, stormwater can be collected in a wetland area and injected into a well to reach a deeper aquifer.

The stored water can then be recovered via the same well and used in the irrigation of crops or ovals…or for non-potable water in households or industry …or even treated to become drinking water.

Urban centres also produce significant volumes of wastewater. This can also be used to recharge deeper aquifers and unlike stormwater is available for recycling all year round.

And in fact managed aquifer recharge helps us recycle urban waste water without the disruption to natural environments that waste discharge can sometimes cause.

Once banked in the aquifer storage periods can vary from short term irrigation support or long term insurance against drought.

Of course there are a whole raft of important social, health, environmental and economic considerations whenever and wherever we use these processes. 

CSIRO helps assess and enable these projects with research into the fate of pathogens and chemicals, protect human health and the environment, and answer fundamental questions like where are the suitable aquifers and how natural processes affect the quality of water during storage.

More and more demand will, inevitably, be placed on our water supply. 

With appropriate research support from CSIRO, managed aquifer recharge can help us create a diversity of water supply options that will meet our future water needs.

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Why bank water?

Regional Australian communities and industries, like agriculture, need greater water security. Banking allows water to be stored long-term for supply during a drought.

Advantages are that underground aquifers can hold a large water capacity and there’s no evaporation. There’s also no risk of mosquitoes or algae.

Towns can also avoid costly water cartage when regular water sources dry up to avoid approaching 'day zero'.

A range of MAR techniques have been developed to manage subsurface water storage safely and to reduce impacts to the environment.

Are there examples of water banking or MAR in Australia?

Australia has traditionally relied on surface water reservoirs for supply.

However, forms of underground storage or MAR have been successfully used in parts of South Australia and Western Australia for over 20 years.

Right now, just 8.3 per cent of Australia’s yearly groundwater extraction is replenished through MAR.

There are no water banking initiatives (i.e. MAR systems operating under a water entitlement framework) currently in Australia. Yet there are successful examples of water banking overseas, such as in California, USA.

What are the opportunities for water banking in Australia?
Our assessments show that water banking is suitable for a range of Australian locations.

Water banking is suitable for a range of geographical settings.

We identified 4km3 of potential storage opportunities in the Murray-Darling Basin.

We are also working with the National Water Grid Authority to identify other regional areas where water banking could support irrigated agriculture.

What locations are suitable for water banking?

Geographical assessments are used to determine suitable aquifers and their capacity to store water.

It’s important to factor in an aquifer’s proximity to both the source of water for recharge and demand for water supply.

This has implications for costs and the economic viability of a scheme.

What’s needed to enable uptake?

Research is needed to inform policy. For example, how surface water and groundwater resources can be conjunctively managed.

Demonstration sites are also needed to show that water banking can be sustainably operated and scaled.

We are undertaking research to understand key enablers to water banking in the Murray Darling Basin and other regions.

How much does it cost?

Water banking can be very cost effective, although costs vary depending on the system applied.

There are a range of MAR systems and the type applied depends on the geographic context and intended end water use, such as for drinking water or irrigation purposes.

In our 2022 study, we modelled a range of scenarios to bank surface water and the costs involved, as pictured below. Average costs are based on two to three different scenarios.

Graphic depicting four MAR systems and indicative costs

Indicative costs for different systems

Recharge release

  • $0.06/kL - Levelised cost
  • Low - Opex
  • Low - Capex
  • 14% -Opex/Capex

Infiltration basin

  • $0.10/kL - Levelised cost
  • Med - Capex
  • Low - Opex
  • 4% - Opex/Capex

Recharge weir

  • $0.20/kL - Levelised cost
  • Med - Capex
  • Low - Opex
  • 4% - Opex/Capex

Well injection

  • $0.30/kL - Levelised cost
  • High - Capex
  • High  - Opex
  • 4% - Opex/Capex
We modelled the indicative water costs across different MAR systems.

What is our Drought Resilience Mission focused on?

Our groundwater experts are:

  • Looking at how best to store water underground
  • Understanding and mitigating risks so water is safe for people and the environment
  • Tailored solution to the need and location
  • Securing demonstration sites.


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