Perth as a city has one of the driest climates in the world.
In this guide, we’ve put together a case study of Perth’s water scarcity problems, and what they have done to address them.
Other countries and cities around the world who are experiencing water stress or water scarcity related issues, might be able to learn something about how to address them.
Summary – Perth Water Scarcity Problems & Solutions
Factors That Might Impact Water Scarcity In Perth
Factors may include but aren’t limited to:
– Low natural rainfall levels in some regions
– The potential side effects of a changing climate, such as declining rainfall, increased likelihood of droughts, increased annual mean temperature, and other climate related changes
– Rising evaporation rates
– Insufficient existing water supply storage capacity/volume
– Declining inflow into surface water supply sources like dams
– Less excess water running off into underground aquifers, in addition to reductions in aquifer recharge rates currently being unknown
– *Additionally, a growing population in a city may in some instances result in increased water consumption (because there’s increased demand).
However, some data suggests that despite Perth’s growing population, Perth’s per capita water consumption decreased, as well as total water consumption over recent decades.
So, whilst population growth might contribute to water stress or scarcity in some instances, it may not have been a relevant factor specifically for Perth
Perth’s Potable & Non Potable Water Supplies – Which One Was Scarce?
Some reporting indicate that Perth has enough potable water (drinking water)
But, Perth was having issues with with their non potable water supply becoming scarce
Where Does The Majority Of Perth’s Water Supply Currently Come From?
Rather than relying mostly on their dams (like they had done in the past), Perth now mostly relies on desalination (for almost half it’s water according to some reports), and also ground water
Perth’s Main Water Sources & Water Supply Solutions Going Into The Future
Some of the main water sources and water supply solutions for Perth going forward into the future might be:
– Ground water
– Using the natural sands and soils around ground water aquifers for storage
– Ground water injection and replenishment (where treated water is filtered through natural sand in the area, and injected into aquifers where it mixes with ground water)
– Waste water recycling and water re-use via dedicated treatment and recycling facilities (Perth is investing in is advanced water recycling plants (where waste water is treated and re-used)
We discuss some of the potential benefits, and also the potential drawbacks and limitations to these water sources and water solutions in the guide below.
It’s worth mentioning that for Perth specifically, making use of their natural sand and soil, and ground water recharge, might make sense on a local level where other cities might not necessarily have the natural environment to make use of these water supply solutions.
Waste Water Recycling As Part Of A Sustainable Long Term Water Supply Strategy
Some water experts identify waste water recycling in particular as perhaps the best long term solution in providing sustainable water supplies, even over desalination
Some of these experts indicate that a major reason might the huge potential to recycle water, because of how much waste water, storm water, and run off water we currently lose, waste, or dump into the ocean
Other Potential Solutions For A Long Term Sustainable Water Supply Strategy
Other potential solutions that might contribute to sustainably managed water supplies might be:
– Diversifying water supply sources, and becoming less reliant on one water source (such as a dam), and also less reliant on water sources that are dependent on rainfall and affected by the natural climate
– Increased cultural and social awareness of the value of fresh water
– Increased acceptance and openness in drinking recycled water
– Strategic water restrictions (water restrictions and water policy can also help decrease demand for water in the short term or long term.)
– More effective water policy
– Backyard bores
– Monitoring annual per capita water usage numbers
– Water conservation and efficiency training for businesses
– Considering initiatives and penalties for corporate water use
– Water saving and water leak detection technology for public water supply pipes
– Upgrading water supply pipes
– Being aware of conflicts of interests relating to political parties and public water supply
– Balancing urban and rural water needs
Different Cities & Towns Ultimately Need Different Local Level Solutions To Their Water Issues
Because each city or town faces different water issues, and has different local variables at play, each city or town will ultimately need their own local water supply solutions and strategies that are designed around their individual problems and also the variables they are working with.
Comparing Perth & Cape Town’s Water Scarcity Issues – Similarities & Differences
We list the potential similarities and differences of Perth and Cape Town’s water scarcity situations at the bottom of this guide.
We’ve also put together a separate case study on Cape Town’s past water shortage which might be complementary to this case study on Perth.
What Type Of Water Is Scarce In Perth?
Water supplies can be divided into two main categories:
– Potable (drinking) water
– And, Non potable (non drinking) water
In Perth’s case, it was non potable water that was scarce, and not drinking water.
theconversation.com indicates that ‘[In Perth’s case …] Drinking water is not running out for Perth, but non potable water is’
Also from theconversation.com: ‘… drinking water supplies [in] Perth are reasonably secure [but] non-drinking water supplies need to be augmented …’
Factors That May Contribute To Water Scarcity For Perth
The following factors may contribute to Perth’s water scarcity issues:
A Changing Climate – i.e. The Climate Becoming Drier
Australia as a country is already the driest continent in the world apart from Antarctica
But, Perth’s climate (as a State within Australia) is getting drier according to some reports.
A drying climate may mean declining rainfall, and increased likelihood of droughts.
These things can impact water supply.
Annual Mean Temperature Anomaly Has Increased
Temperature has the ability to impact different aspects of the natural water cycle (such as evapotransporation), and ultimately water supplies.
[Annual mean temperature anomaly has increased] 1℃ in southwest Western Australia in the past 40 years (theconversation.com)
Decreasing Rainfall/Precipitation Levels
Different sets of data show both annual and multi decade reductions.
This means there’s potentially less inflows for surface water and ground water sources
[On the yearly scale:]
Perth’s annual rainfall has been declining by about 3mm per year on average (theconversation.com)
[And, also on the decade, or multi decade scale:]
Average rainfall levels have decreased in the past few decades (bbc.com)
[Perth’s] rainfall has declined almost 20 per cent since the 1970s … (abc.net.au)
From bbc.com: ‘Decreasing rainfall means less rain is flowing into dams and other water supply sources …’
Decreasing Water Inflows Into Water Supply Sources
Decreased rain flowing into water sources can be due to less total rain, but also other factors, such as decreased inflows into water sources, and also higher rates of evapotranspiration
Some of the estimates of how much less water is flowing into Perth’s water sources compared to the past show significant reductions
[Only about …] about one sixth of the water is currently flowing into dams compared to the past (bbc.com)
Water flow from rainfall into Perth’s dams has slumped by 80% since the 1970s (theguardian.com)
… the amount of water flowing into [Perth’s] dams has fallen from an average of 300 billion litres a year to just 25 billion litres (abc.net.au)
theconversation.com indicates what the main causes of reduced inflows might be:
… inflows to water reservoirs are decreasing as a result of decreased rainfall and [decreased] river inflows
Rising Evaporation Rates
As we mentioned above, evaporation rates rising can be one of the factors that lead to less water flowing into water supply sources, as water evaporates before it can inflow into these sources.
Water may also evaporate before it can percolate into groundwater aquifers.
The overall effect [of rising evaporation rates is] that soils and vegetation are often dry, meaning that rainfall will be lost to evapotranspiration rather than running off into rivers and dams, or recharging underground aquifers (theconversation.com)
Previous Supplies Of Freshwater Did Not Have Sufficient Capacity To Meet Demand
A city needs to have enough water supply capacity (along with renewal rates) to meet the total consumption (and depletion rates) of the city.
There’s various factors that impact the water consumption of the city, with population size being just one example, and water consumption rates by the various industries and sectors being another example.
Perth wasn’t receiving enough water to their supply sources compared to the demand on those sources.
[In 2013] Perth’s dams received just 72.4bn litres of water – far less than the 300bn currently demanded by Perth’s two million-strong population (theguardian.com)
There’s Less Excess Water Running Off Into Some Storage Aquifers, & Groundwater Recharge Rates Are Unknown
Underground aquifers usually recharge when water percolates through the soil into the aquifer.
However, in Perth’s instance, there’s been less run off into aquifers, and reductions in groundwater recharge rates are currently unknown.
According to theconversation.com:
About 70% of local road runoff and half of roof runoff already recharges the shallow unconfined aquifer …
But, there’s been less excess water from winter rains.
Unlike dam inflows, … the full scale of the reduction in natural groundwater recharge rates [in currently unknown]
*A Growing Population
This factor comes with an asterisk for the following reason …
A growing population can lead to increased water consumption, because there’s more demand on water supplies from a greater number of people
However, in Perth’s case, per capita water consumption appears to have fallen despite a growing population, and their overall water demand decreased over one decade long period.
So, this wasn’t a factor in their water scarcity issues.
Water restrictions and other water policy changes might traditionally impact per capita water consumption totals.
It’s also important to distinguish between long term water consumption trends, and also year to year trends, when analysing water consumption vs population growth trends.
Perth’s population grew by more than a third from roughly 2004 to 2014 (bbc.com)
… despite a rising population, Perth’s water demand was down by 8% [in 2013] compared with 2003 [and] Water consumption has fallen from 191,000 litres to 131,000 litres per capita per year over the past decade in [Perth].
Perth’s consumption can be compared to San Diego’s consumption, [which] is an estimated 249,000 litres per capita per year
San Diego has a population of 1.41 million compared to Perth’s 1.985 million, according to different online data.
So, Perth may have a similar water consumption volume as San Diego, but have much more people in the population.
Where Does The Majority Of Perth’s Water Supply Currently Come From?
Where Does Majority Of Perth’s Water Supply Come From?
Mostly desalination (around 50% according to some reports), followed by ground water.
According to theconversation.com: ‘Perth now relies chiefly on groundwater and desalination rather than dams’
As of 2018, desalination provides almost half of Perth’s water needs while the other half comes from ground water (abc.net.au)
Where Other Australian Cities Get Their Water Supplies From
theconversation.com has a useful resource where they show the water supply of Australia’s major cities by water supply source
Perth’s major water supply sources are desalinated and ground water, with surface water and recycled water third and fourth.
Another city, Adelaide, gets additional water supply via transfer from another state’s water source (also known as transboundary water transfers).
So, we can see that different States in Australia get their water supply from different sources.
How Perth Is Addressing Their Water Scarcity Problems
Perth is mainly addressing their water scarcity problems by reducing their reliance on dams for their water supply, and diversifying to other water sources and water solutions.
They’ve added the following main water solutions as part of their overall water strategy:
– Dedicated water recycling and waste water treatment
– Treating waste water, filtering it through local sands, and injecting it into ground water aquifers where it mixes with ground water, and rechargers aquifers
– Using local soils and sand for water storage of excess runoff
– Plus other water supply solutions
According to theconversation.com:
Although both [groundwater and desalination] are much more expensive than dam water, desalination and groundwater replenishment look set to secure Perth’s drinking supply, because seawater is virtually unlimited, and wastewater availability increases in line with the city’s growth …
[Some commentators on Perth’s water strategy indicate that water recycling may be better than desalination:]
Perth professors argue that treating and recycling waste water is a better long term approach than desalinations plants (abc.net.au)
The abundance of seawater makes desalination an attractive water supply option
Although, the cost of desalination compared to dam water may be a challenge for the future
Large water desalination plants using sea water from the Indian Ocean via Perth can get up to half it’s drinking water from these [two] desalination plants (bbc.com)
These plants use reverse osmosis seawater desalination technology and provide nearly half of the city’s water supplies (theconversation.com)
As of 2018, these plants have been able to provide one-trillion-litres of water (abc.net.au)
Water Recycling & Treating Waste Water
The potential to re-use the abundance of wastewater that is currently waste or dumped into the ocean makes water recycling and waste water treatment an attractive water supply option
This may particularly be the case for Perth according to some ‘water experts’
Water recycling plants may also have decent production capacity.
[Perth has a large amount of waste water that goes straight into the ocean]
[Perth should be sending waste water] into recharge or treatment to produce good water for public open space, even potable water
The technology is there to treat any water — waste-water, storm water, any kind of water can be treated to perfection
From theconversation.com: ‘About 140 billion litres of treated wastewater are discharged into the ocean every year in the Perth-Peel region …’
From theguardian.com: ‘An advanced water recycling plant can be expanded to produce 28bn litres of water each year when required …’
Recharging Groundwater Aquifers
Perth’s local yellow sands might be suitable for helping filter treated waste water (and even help improve the quality of the water too)
Man made recharging of groundwater aquifers via this filtering and injection method may also help speed up the overall recharge rate of aquifers, which can be very slow to recharge naturally
Water can then be extracted for specific uses such as irrigation, but may also be able to be used for drinking water.
This has been a decade long trial for Perth, that some reports indicate could provide a larger % of water in Perth’s future.
The process may not only improve water quality and recharge aquifers, but may have environmental benefits too.
In addition to filtered and injected water, water can also runoff naturally into aquifers from road runoff, and roof runoff.
And, there may also be additional water that can be redirected into these natural sands that currently aren’t being filtered or injected into them.
How Much Water Is Going Into Sands & Groundwater
According to theconversation.com:
About 70% of local road runoff and half of roof runoff already recharges the shallow unconfined aquifer [in Perth], because it is the cheapest way to dispose of excess water in areas with sandy soils.
… [but] treated wastewater is [also] added to these aquifers where it blends with the groundwater and is extracted later for water supplies
[There’s also] … 7 billion litres [of treated waste water] are infiltrated into the sands as a means of disposal where there isn’t an option for ocean outfall.
Potential Benefits Of Water Injection & Infiltration Through Natural Sands
Investigations have … shown that the quality of treated wastewater [that is usually discharged into the ocean] can be greatly improved when infiltrated through the yellow sands into the limestone aquifer in the western part of Perth.
Recent investigations of [the] land disposal sites have shown them to be effective in protecting wetlands from drying [and] … green spaces, which are needed needed to provide much-needed cooling … as Perth gets even hotter and drier … and [also] to safeguard … trees
Also from theconversation.com:
As well as reducing discharge costs, this practice [of using local natural sands and aquifers to store excess run-off from roads and roads] helps to ensure that bores do not run dry in summer.
Using Injected Water For Non Potable Water
[The water] is suitable for [both] … public and private irrigation … after a few weeks’ residence within the aquifer (theconversation.com)
Using Injected Water For Drinking Water
[The] treated wastewater … injected into underground supplies [has also been] re-used as drinking water (abc.net.au)
What % Of Water Supply Groundwater Replenishment Could Provide In The Future
From theguardian.com: ‘Groundwater replenishment could supply up to 20% of Perth’s drinking water needs by 2060 ‘
Additional Water That Could Be Redirected To Aquifers
[Also according to theconversation.com, there might be additional sources of water that Perth could redirect into their existing storage aquifer that they currently aren’t utilising:]
Perth also has large main drains that are designed to lower groundwater levels in swampy areas and prevent inundation.
Some of these waters could be redirected into the aquifer where there is a suitable site [to help in recharging groundwater aquifers]
Using Local Sands For Excess Water Storage
Perth’s local sands might be suitable for storing excess runoff from different sources, where it might otherwise be wasted or lost
Perth’s hydrology means that they can use their local natural sands and aquifers to store excess run-off from roads and [roofs]
Other General Water Supply & Water Strategy Solutions
Diversify Water Supply Sources
Relying on 2, 3 or more water supply sources makes a city’s water supplies less vulnerable to one point of failure.
If one water supply is diminishing or at risk, there are other options.
In Perth’s case, they are diversifying away from dam water supply.
It also helps if new water sources don’t rely on natural rainfall or aren’t impacted as much by the climate – which desalination and water recycling aren’t.
In theory, it means Perth may be better protected from the variability in the natural water cycle and a changing climate because of this.
Awareness, & Cultural/Social View Of Water
Citizens becoming aware that water is a scarce, valuable resource that is not to be wasted.
This means they are theoretically less likely to waste it than if cultural and social norms didn’t place a high value on water.
Openness to Drinking Recycled Water
Citizens have to be open to drinking recycled water
And, this might be easier to do if citizens view water as a valuable resource.
For households (particularly for gardens, lawns and sprinklers), and on a per person basis.
But, restrictions for large water users (in different sectors) is something that might be considered too.
Some citizens in Perth have backyard bores … more than a quarter have them for watering their gardens.
These bores provide another water water source other than what’s supplied publicly.
Become Less Reliant On Rainfall
Perth diversified to other sources of water like desalination, and found ways to utilize water recycling, water storage, and ground water recharge.
These methods places less dependence on rainfall to top up groundwater and surface water sources like dams.
Monitor Per Capita Water Usage
This might be an indicator of how effectively water is being used.
Knowing both potable and non potable water per capita water usage can help cities more effectively track their water management.
Water Saving Training, Schemes & Potential Penalties
Provide businesses with water management training, and the tools for data-gathering.
Certification schemes for water conservation/management, along with fines might help.
According to some reports, a total of 330 businesses have reportedly saved enough water to fill the equivalent of 20,000 Olympic-sized swimming pools since the Water Corporation started [a project like this] in 2007
Water Saving Technology
According to theguardian.com:
Organisations have made use of acoustic listening equipment to locate pipe leaks, helping to reducing water use by 10%, & other organisations have cut their water use by 25% by reducing the flow of their taps and installing dual-flush toilets, among other things.
Perth’s largest theme park, Adventure World, checks water levels and pressure using real-time monitoring. If a leak is detected, maintenance to resolve the problem can be quickly deployed. Around 30m litres of water have been saved in the past two years this way. The theme park has also installed two new filters, at A$100,000 (£46,700) a piece, saving 30,000 litres of water a day in peak season (will take 5 years to pay itself off)
Emphasise The Importance Of Corporate Social Responsibility
For businesses and organisations to save water or use it efficiently.
Other Water Saving Measures
– Using drains and ditches to channel water run-off into water storage areas
– Conserving water use particularly during summer – where it can be more of an issue
– Water restrictions on washing cars, using water on gardens, sprinklers
– Applying user pays water rates
– Metering of ground water users, like farmers and businesses, and monitoring for unproductive water use
– A problem that needs to be addressed is where water is in short supply, and water security tends to equal electoral security.
There is a conflict of interest here.
So, we need to remove the political conflict of interest from water supply … independence and guarantee of tenure are ways to do this for certain water supply positions and organisations
– Even though cities might solve some of their water scarcity issues long term, towns and rural areas need adequate support from state and national government too.
So, water supply solutions aimed at these areas is important – we can’t just neglect important towns and farming or rural regions within a state or province
Potential Challenges, Drawbacks & Limitations To Perth’s Water Supply Solutions & Strategies
There may be challenges, drawbacks and limitations to some of the solutions and water strategies for Perth listed in this guide.
Some of them might include:
We outlined the potential benefits and drawbacks of desalination plants in this guide, but a summary of important drawbacks might be that they:
– Can be expensive to build and operate
The cost to build can be in the millions and sometimes billions
And, operations costs and electricity costs can be expensive too
– Water may be expensive for consumers compared to other water sources
The average Perth household’s water bill has tripled since 2005–06 [up to 2015], even though water consumption per capita has dropped substantially over the past decade.
This adds to cost of living [too]
– Can be energy intensive
– Can emit air pollution and greenhouse gases indirectly
This is especially the case when coal and fossil fuels are used as energy sources
Western Australian carbon emissions per capita are now the highest in Australia and among the highest in the developed world [and, desalination plants only add to this] (theconversation.com)
– Are responsible for a waste product ‘brine’, which is a concentrated salt water by-product
The marine environments of Perth’s desalination plants are sensitive to the hypersaline discharge that is produced in the purification process (theconversation.com)
Water Recycling & Waste Water Treatment
Groundwater Recharge, & Water Storage In Sand
– Relies on local sands and conditions that may not be available in some regions worldwide
Not every city or town has local hydrology and geology that allows them to use these water solutions
– Boreholes bored into groundwater sources can deplete the aquifer they withdraw from
Citizens having backyard boreholes can compromise the water available to the public supply via groundwater and aquifers
Comparing Perth & Cape Town Water Scarcity Issues – Similarities & Differences
Perth and Cape Town had some similarities, but also some differences in their water scarcity issues.
Some reports also indicate that their decision makers and water management authorities addressed the issues in different ways too.
Some of the similarities and differences between these cities’ water issues might be:
Perth faced some of the same challenges as Cape Town (who experienced a recent water shortage) as a city. Some of these common challenges might include:
– Both have experienced population growth recently, and, future population growth is forecast too
– Similar climatic conditions, such as a dry climate
– Possible side effects of a changing climate
– Decreasing rainfall
– Being drought prone
– Decrease of stream flows and water flows into dams
– Both relied on their dams
– Plus, other challenges
[Perth faces] very similar climatic conditions to Cape Town
Perth, much like Cape Town, was once almost entirely reliant on its dams
There’s … been significant population growth [in both Perth and Cape Town over the last few years to decades, and more population growth is expected] (theconversation.com)
– However, unlike Perth, Cape Town stayed somewhat reliant on their dams to provide a public water supply
– Perth sourced an increasing amount of water from desalination and groundwater (diversifying their water supply), and Cape Town didn’t. To increase per person water capacity, Cape Town was since reported to be looking into building several small scale desalination plants
– Perth could make long term decisions to deal with a changing climate, whilst Cape Town couldn’t
– Cape Town at one point had far lower daily water restrictions to address water shortages, whereas Perth’s water restrictions were always far higher
– Perth has a population size about half the size of Cape Town’s
[Perth has] been in a position to make long-term decisions to deal with climate change [and Cape Town hasn’t]
[In the midst of Cape Town’s water shortage, there was] strict water restrictions amounting to 50 litres per person per day — Perth residents use an average of 335 litres a day
Perth is half the size of Cape Town in terms of population …
Perth has progressively sourced more and more of its supply from desalination and from groundwater extraction, [while] Cape Town has not done this [yet]
Potential Ideas For Cape Town
Looking to diversify their water supply sources in the future (potentially with desalination and water recycling), becoming less reliant of water sources that are dependent on natural rainfall and affected by the natural climate, and increasing their per person water capacity, might all be good solutions for Cape Town to consider as part of their water supply strategy.
Whilst Cape Town didn’t seriously invest in desalination prior to their last notable water crisis issue, some reports indicate they are now attempting to set up a number of small desalination plants to increase their water capacity/water supply per person
Other Water Stressed & Water Scarce Cities
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