Water is our most precious resource; it underpins all aspects of life. Yet, still we hear that there’s not enough water and that there’s a water crisis threatening our health and environment. What happens when water runs out? How do we ensure water security in the future?
In reality, the world won’t run out of water. Water does not leave Earth, nor does it come from space. The amount of water the world has is the same amount of water we’ve always had.
However, we could run out of usable water, or at least see a drop to very low reserves.
As populations grow, more water is needed to sustain industries, households, and the environment. Not all water can be used for these purposes, and individual countries and states manage provision of potable (safe enough to drink) water in different ways.
Beyond this, climate change impacts the amount of usable water we can collect, as well as the processes that go into cleaning that water up for use.
So what can we do about it?
How clean is my water?
In Australia, standards for potable water are dictated by the Australian Drinking Water Guidelines. This helps inform when water is chemically considered safe enough to drink by guiding what types of molecules should and should not be present in the water, what types of disinfectants are used, as well as the impact such water has on health.
All the water that comes through your tap from a “town water” system will have been subjected to these guidelines. Water retrieved directly from private bores or rainwater tanks will not have been.
Water is constantly monitored through the year to ensure continued, safe standards.
Where does my water come from?
Our water largely comes from rainwater that enters our major water ways (ie, in South Australia’s case, the river Murray).
Some countries with cooler climates collect snow- and ice-melt that runs down from mountains, but this is far less common in Australia.
The problem here is that rain is unpredictable beyond a few days, so there’s no guarantee of long term, sustainable rains.
Water and climate change
Water supplies in Australia rely on rain. But as the climate shifts and weather events become more extreme, the supply of rain will become significantly more sporadic.
That means it will be harder to rely on that source. Instead of putting all our eggs in one basket, we’ll use other diverse methods of supplying water to ensure there’s an adequate amount in the system under unpredictable conditions.
For example, desalination plants and water recycling are the sorts of things we’ll do to become climate resilient; if there isn’t water passively coming into the system, we’ll need to make it ourselves or reuse what we’ve got.
Why is water management so important?
Australia is a dry country for the most part, and each state has different water accessibility and needs. Droughts are frequent, which often leads to water restrictions, and there is little guarantee as to when the rains will come.
On the other hand, flooding doesn’t guarantee a good supply of usable water, either. When heavy rains fill up rivers, the water flows with a high velocity and dislodges and carries significantly more debris with it.
This means that it requires much more intensive treatment, which not every facility has the capacity to manage.
Beyond this, climate change has multiplied the unpredictability of rainfall, and we know there are likely to be plenty more droughts and extreme weather events that will compromise the availability of water.
Together, this means actions must be taken to manage and prepare for water-insecure times.
Water management therefore covers multiple areas: improving our current water supply chain, encouraging changes in habits to move towards a circular water economy, and ensuring sustainable water use for industry, households and the ecosystem.
All water management actions are based on chemistry, climate science, mathematical modelling, engineering and policy.
What is water security?
This refers to how comfortably and sustainably we can guarantee water supply.
In our current water cycle, water comes to us from places like rivers, aquifers (which hold groundwater) and reservoirs, which are mostly filled by rain, and desalination plants that convert water from salt water to fresh water.
Water leaves our industries and homes via sewage and wastewater networks. Some of it is reused for irrigation, but most of it leaves the system.
However, this whole process relies on getting enough rain, which is, as we’ve established, is both unpredictable and changeable.
A water-secure nation would instead operate on a circular water economy. That is, water once in the system would largely remain in the system, rather than being discarded as waste.
Such a system can be based on frequent and predictable rainfall, or on changing our water practises sufficiently to decrease waste.
For example, NEWater factories in Singapore collect and clean waste sewage water for reuse. Chemically, the recycled, potable water is the same as “fresh” drinking water on its first use, because the recycled water goes through rigorous chemical cleaning.
This means that the supply of water in the system is relatively constant, and there’s less reliance on natural cycles of weather, which are shifting due to climate change. Instead, water becomes part of a sustainable, secure, circular economy.
Being literally out of this world, the International Space Station can’t rely on the luxury of rain, so astronauts survive thanks to a high-altitude circular economy of recycling water.
Of course, a circular economy water system still needs water to come into the system, and also requires more restriction and regulation of how water is used.
What can we do to become more water secure?
This is a big question, but scientists, engineers, policy makers and water managers are continually preparing for the future. Join us for Cosmos Briefing on Thursday 6 May to hear more from the experts.
Dr Deborah Devis is a science journalist at The Royal Institution of Australia.
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