Day Zero and pathways to water security for regional towns

By Declan Page, Oswald MarinoniFebruary 27th, 2020

Day Zero marks the day when residential taps are turned off — a reality for some regional and rural towns across Australia. When this current drought breaks, we can’t lose sight of the fact that another drought will inevitably come. We have to prepare for water security now.
A dry dam from the sky
Aerial view of the Cotter Dam during drought

Aerial view of the Cotter Dam during drought. Cotter Reservoir is a supply source of potable water for the city of Canberra. (Image: CSIRO)

Day Zero approaches

Most of us will have heard of Day Zero by now. Day Zero marks the day when residential taps are turned off – when water is carted to local collection points. It happened in Cape Town, South Africa in 2017; the wide-spread water shortages caused social tension, and had environmental and economic impacts, with damage to tourism and agricultural industries.

In Australia, Day Zeros have been reported for several regional and rural country towns. For instance, in Stanthorpe, Queensland, the town officially ran out of water in January 2020 and has had to start carting truckloads of water every day to meet residential demand.

Luckily, much needed recent rainfall in February 2020 has helped many communities replenish their water supplies. However, much like the Millennium Drought, this current drought highlights the need for improved water security. Water security remains inadequate for many rural and regional communities, with multiple towns at risk of reaching, or already at, Day Zero.

While the current drought may have broken in places like Sydney where water restrictions are being eased now is actually the ideal time to plan and prepare for the next drought, which we know will come. But how can that be done?

The impact of water insecurity

A map of towns in Queensland and New South Wales that are running out of water.
This image was created on 27 February 2020, using information from an ABC News article (published on 15 February 2020) on water security. The ABC's interactive map also includes towns in South Australia, the Northern Territory and Western Australia.

This image was created on 27 February 2020, using information from an ABC News article (published on 15 February 2020) on water security. The ABC’s interactive map also includes towns in South Australia, the Northern Territory and Western Australia.

Terms like “water security” actually suggest the exact opposite: water insecurity. Water insecurity can result from acute impacts (events such as droughts), chronic impacts (such as a drying climate), and water quality risks (events such as post bushfire catchment runoff can make reservoirs and rivers undrinkable) or a combination of these factors.

Water insecurity has many negative impacts on human health, the environment and the economy – particularly in regional areas that rely on agricultural industries. The possibility of reaching Day Zero can never totally be eliminated. However, it can be made tolerable if the threat of water insecurity is more actively managed.

Setting objectives for water security

Instead of seeing Day Zero as a looming threat, decision-makers could approach water security as an objective that they strive to meet; where water insecurity is no longer an issue for the community.

Investment in response to water security risks can be approached from a cost-benefit perspective, or from a tolerable versus acceptable risk perspective. The classical cost-benefit approach compares the costs of a water security intervention (investment in infrastructure, for example) with the marginal economic, social and environmental benefits gained, with benefits also expressed in dollars. A town or city’s ‘residual water security risk’ is the level of risk (of running out of water) that remains, even after implementing water security measures.

However, it can be problematic for decision-makers to adopt either the ‘objective-setting’ or ‘cost-benefit’ approach for a variety of reasons. For instance, within a ‘cost-benefit’ approach it’s generally difficult to put a dollar value on the social or environment benefits. If benefits are intangible, a multi-criteria approach, which does not require every criterion to be expressed in dollar units, can be an option.

Alternatively, the ‘acceptable risk’ approach implies that there is some threshold beyond which risk is unacceptable, but this may differ between individuals and society. Nevertheless, the absence of a minimum risk also seems to be unacceptable. Notwithstanding the difficulty of establishing water security risk-based targets, metrics can still be developed.

How much is enough water security?

To enjoy water security, several dimensions need to be managed including the needs of human consumption and sanitation, environmental water needs as well as water needs of local economies. Internationally, water security indicators have therefore concentrated on the volume of water needed.

For example, the World Health Organisation (WHO) has defined water security in terms of access for human health and sanitation risks:

  • No access: Less than 5 litres, per person, per day. (No water security)
  • Basic access: 20 litres, per person, per day. (Basic water security)
  • Intermediate access: 50 litres, per person, per day. (Effective water security)
  • Optimal access: more than 100 litres, per person, per day. (Optimal water security)

Meeting basic water needs for food security and agriculture also poses challenges. In Australia, 50-70% of water use supports irrigation, in addition to the rainfall used for rain-fed agriculture and grazing. These metrics of basic water needs can provide a baseline against which recent trends and future projections can be understood, informing management decisions.

Water falling from tap into a bucket
According to WHO, optimal access is more than 100 litres, per person, per day. (Image: FeedPix)

According to WHO, optimal access is more than 100 litres, per person, per day. (Image: FeedPix)

Investment pathways to water security

Investment decisions should be informed by measuring the reduction in water security risk. Currently, investments in water-related infrastructure generally do not indicate how much water security risk has (or could be) decreased.

For example, the recently completed Wentworth to Broken Hill Pipeline is a major piece of public infrastructure. It supplies Broken Hill with up to 37.4 ML of raw water per day, via a 270-kilometre pipeline from the River Murray near Wentworth to Broken Hill. Monitoring the effectiveness of this approximately $500 million investment (compared to other water security investment options, such as water banks or even direct potable reuse) in the context of water security metrics is seldom done explicitly.

There are several options for improved water security around Australia, including:

  • Increased water recycling of wastewater
  • Use of desalination technology
  • Building surface water dams
  • Use of aquifers and water banking
  • Demand management and water restrictions
  • Improved efficiency of systems

‘Pathways to water security’ refers to the sequence of investment decisions taken to reduce water security-related risks. The most effective investment options for any given community depends both on the context and the pathway taken. Often past investments can both open or close alternatives.

There is also emerging evidence about pathways to water security in terms of institutional reform and infrastructure, as well as the interaction and sequence of these two pathways. For example, the operation of effective water banks via Managed Aquifer Recharge (infrastructure) requires well-defined property rights (institutional reform). These water property rights determine who gets access to water and how decisions are made. Property rights and water sharing across state boundaries establish the benefit and cost sharing needed to spur investments in infrastructure.

Pathways deliberately address questions of sequencing, lock-in effects (the order in which infrastructure is built and the option is foregone, as a result), and cumulative risks (the sum of all risks). So far, methodologies for risk-based appraisal of robust infrastructure investment pathways have been applied in a relatively small number of settings.

Case studies from Australia and abroad

Decision-makers in Australia and abroad are using some of these approaches and alternatives to improve water security. For example:

  • Perth, Western Australia: Australia’s first full-scale Groundwater Replenishment Scheme is located in Perth, Western Australia. It started recharging recycled water to Perth’s deep aquifers in 2017.
  • Orange, New South Wales: In 2019, a stormwater harvesting scheme and a pipeline recently provided a third of Orange’s water supply, adding up to more than 790 megalitres of water over six months.
  • Beaufort, South Africa: The community of Beaufort West, blends 20 per cent reused water into its water supply from local dams.
  • Arizona, USA: The Arizona Water Banking Authority stores water in underground aquifers, to earn long-term storage credits. These credits can be recovered (pumped) during a shortage to provide back-up water supplies (“firming”) for Arizona water users.
  • Big Spring, USA: Severe drought in 2014 prompted Big Spring and Wichita Falls to recycle wastewater effluent for drinking water use.
Soil aquifer treatment system filling with treated wastewater.

Soil aquifer treatment system filling with treated wastewater. (Image: CSIRO)

Looking ahead: using ‘pathways to water security’ in Australia

Perhaps decision-makers are fearful of using approaches that seem complex or conceptually challenging. However, the assessment of risks and ‘pathways to water security under uncertainty’ represents only a small change to what is already done when making water security decisions. The existing tools of risk analysis and management are well-established and provide a methodological toolkit for appraising pathways to water security.

With Day Zero again in the public space, it’s arguable that there has never been greater attention on water security in Australia. There will be different water security pathways for different communities, but how those decisions are made requires transparent, robust and defensible decision making. A better understanding of the water security risks is the foundation for good decision making, policy reform and infrastructure investments to increase resilience.

When this current drought breaks, we can’t lose sight of the fact that another drought will inevitably come.

This is the moment we must start preparing for it.

Dry dam with very little water
The Victorian side of Lake Hume, at 4% in 2007 (image: Tim J Keegan via Flickr)

The Victorian side of Lake Hume, a major dam across the Murray River, at 4% capacity in 2007 (Image: Tim J Keegan via Flickr)


  1. Wondering what your thoughts are on cloud seeding? Tasmania has a 30 year history with seeding. Two sites on the mainland identified as suitable over catchments. Ground based seeding currently operated by Snowy Hydro could be augmented by aerial seeding. Would appreciate your thoughts and comments.

    1. Cloud seeding, as per earlier comment – any thoughts?

    2. Hi Adrian,
      Thank you for your email. Cloud seeding is only effective in some areas, and only when rain does fall in that area. CSIRO no longer undertakes research into cloud seeding. You can view our history with cloud seeding on CSIROpedia.
      Kind regards,

  2. Kate, wonderful information – thank you very much. Will consult with Monash University and if I am lucky might get a trial going. Newcastle based aviation company now has the aircraft used for Tassie Hydro seeding and they are open to discussion on a trial. I just need to contact Snowy Hydro to see if they would benefit from additional aerial seeding to add to their ground based program.
    Thanks again Kate.
    Regards, Adrian

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