Uses for stormwater and improving how stormwater is managed
Stormwater is generally managed through the use of drains, pipes and
channels that ultimately discharge the untreated water into larger waterways;
however, stormwater can also be captured and recycled for use. This chapter
examines stormwater harvesting, which is the recycling component of stormwater
management. This chapter also considers the concept of water sensitive
urban design, which seeks to better integrate water sources such as stormwater
into urban planning.
Stormwater harvesting involves the capture, treatment, storage and use
of urban stormwater runoff. Stormwater harvesting is differentiated from
rainfall or roof‑water harvesting projects, such as rainwater tanks.
Rainwater harvesting, however, can ultimately reduce the volume of stormwater
that enters drains or creeks. Consequently, rainfall harvesting projects such
as rainwater tanks were raised in evidence and are discussed in this chapter.
Potential non-potable uses for stormwater include:
agricultural uses, such as for horticulture, trees or woodlots,
pasture or fodder, dairy pasture, lucerne, flowers, orchard, nursery,
vegetables, viticulture, hydroponics and turf farms;
fire-control uses, including for controlling fires, testing and
maintenance of fire-control systems and training facilities for firefighting;
various municipal uses, such as roadmaking, dust control and
residential and commercial property uses within buildings (such
as toilet flushing) and for garden watering, car washing, water features and
systems (ponds, fountains, cascades) and utility washing (such as washing
paths, vehicles and fences); and
industrial and commercial uses, such as for cooling water,
process water and washdown water.
As will be examined in this chapter, however, there is potential for
potable use of stormwater. Whether stormwater is used for non-potable or
potable purposes, the various operational, environmental and health risks it
presents need to be addressed. Public health and environmental risks arise as stormwater
contains coarse materials and organic matter (such as sediment and leaves), chemicals
and disease‑causing microorganisms (pathogens) that need to be managed or
Operational risks for stormwater harvesting projects also arise because of
stormwater quality. Among other problems, coarse and organic material carried
by runoff can block pipes; high nitrogen and phosphate levels may support algal
growth; and high iron concentration or high levels of calcium carbonate may
block irrigation systems over time.
Examples of stormwater projects and
Many submitters highlighted stormwater and rainwater harvesting efforts
that are currently underway. Stormwater and rainwater harvesting schemes
outlined in submissions included the following:
'Green roofs' in dense urban environments that 'harness rainfall,
reduce heat island effects, insulate buildings, and reduce energy costs for air
Mandatory rainwater tanks in south-east Queensland, a policy that
was discontinued in 2013.
Stormwater Australia contended that public health arguments against rainwater
tanks 'ignore the differences in risk posed by centralised, reticulated systems
(where failures expose many to health risks) and private supplies'.
Stringybark Creek in Melbourne, where 'leaky tanks' and onsite
treatments 'have been used to reduce the impact of a typical, developed suburb
on the surrounding creeks and ecosystems'.
The Blackmans Swamp stormwater harvesting scheme in Orange, New South Wales,
which can provide up to 40 per cent of Orange's total water needs.
Stormwater is being utilised by local governments for parks and gardens.
The City of Melbourne advised that 25 per cent of the water it uses,
primarily for parks and gardens, is supplied by harvested stormwater.
One of the City of Melbourne's stormwater harvesting schemes is
located in Fitzroy Gardens.
According to a description of the project published by the City, Fitzroy Gardens
'is an ideal location to capture and treat stormwater runoff' because Fitzroy
Gardens includes the 'natural low point for the surrounding 67-hectare
catchment' and 'rainwater naturally flows there'.
The following description of the Fitzroy Gardens scheme provides an
insight into the design and operation of a stormwater harvesting project (an
illustration of the operation of the Fitzroy Gardens system is at Figure 3.1):
The treatment process begins with a gross pollutant trap that
removes large pollutants, such as litter and leaves. The water then flows to a
sedimentation chamber. In this chamber, we remove suspended particles of
pollution such as fine sands and oils.
Next to the chamber is the primary storage tank, which can
store four million litres of partially treated water. From here, the water is
pumped to the surface where a biofiltration bed naturally removes invisible
pollutants like nitrogen and phosphorus. One million litres of treated
stormwater is stored in a secondary tank and used for irrigation. Any excess
treated water returns to the stormwater drains.
Finally, before the water is pumped to the Fitzroy Gardens
irrigation network, it is passed over ultraviolet (UV) light tubes to kill any
Figure 3.1: Stormwater harvesting system,
Fitzroy Gardens, Melbourne
Source: City of Melbourne, Urban
water: Fitzroy Gardens case study, http://urbanwater.melbourne.vic.gov.au/wp-content/uploads/2015/02/Urban-Water_Fitzroy
-Gardens-Stormwater-Harvesting-System.pdf (accessed 18 September 2015), p. 2.
A project that the committee received extensive evidence on involves
Michell Wool in the City of Salisbury, which is located in the Adelaide metropolitan
area. Mr Bruce Naumann, who is currently the manager of Salisbury Water at the
City of Salisbury, explained to the committee that in 1995, he was
employed by Michell Wool and assigned the task of finding an alternative water
supply for the business. At the time, Michell Wool was using three million
litres per day of mains water to wash greasy wool supplied by the farms. Mr
Naumann described the situation as 'just crazy', as Michell Wool was using
water that had been treated to drinking standard and paying 'a small fortune'
to SA Water. Mr Naumann outlined how the stormwater project for Michell Wool
We sought the help of the City of Salisbury and, having dealt
with state government departments—and I will not bag state government too
much—we had Salisbury come out and say, 'Yes, we can help you.' It was a
customer service ethic that still exists today, and much of our focus in the
City of Salisbury is on trying to sustain and maintain existing industry and
attract new industry to create jobs for local people. We set up a partnership
between the City of Salisbury, the federal government and Michell Wool. Very
importantly, it was the first one where we got significant funding from the
federal government. The federal government funded the clean seas program,
giving us $1 million; Michell Wool put up $1 million; and the City of
Salisbury put in $1 million, creating the Parafield Partnerships Urban
With the $3 million in funding, four hectares of land was leased from Parafield
Airport to build wetlands needed for the project. Mr Naumann explained that,
from the perspective of the City of Salisbury, this was 'our first major step
into water harvesting'. Mr Naumann added that the Michell Wool project 'is
still the cornerstone of our scheme today' and is 'many times bigger', with over
Mr Naumann highlighted how the stormwater harvesting has helped to support
Michell Wool's operations and, in turn, the local economy:
Twenty years ago, back before the collapse of the wool
industry, they were processing 20 per cent of the Australian wool clip, and
there were something like 19 competitors in Australia. Most of Australia's wool
was actually being scoured before it got processed further, so at least there
was early-stage processing. The sad thing today is that it is almost all going
straight overseas from the farm. Michell themselves dabbled in building a plant
in Shanghai, and they are now actually moving production from Shanghai back to
Salisbury. They are, sadly, the only wool-scouring or wool-processing operator
in Australia now. Everyone else has gone bust. They certainly give us credit
for that. They get a very good deal on their water, very cheap—unfortunately,
because I have now changed sides! I am now on the Salisbury side rather than
the Michell side, trying to sell water. Certainly, the water price they have
does not help our bottom line. But they made the investment when it was in the
very early stages and it was a very high risk project. They put their money out
there and they have reaped the rewards. But so has Salisbury, and jobs in that
area have been retained.
The committee was also informed of the Oaklands Park project in the
City of Marion, which is also located within the Adelaide
metropolitan area. The project involves between 400 and 500 megalitres per
year. Dr Robin Allison from Stormwater South Australia highlighted the
multidisciplinary aspects and multiple objectives of the project:
One that comes immediately to mind for me is one in Oaklands
Park in the City of Marion, mainly because it was a project that was very much
multidisciplinary and had multiple objectives. It is a stormwater-harvesting
project, but that was not its only objective. It was the most visited park in
the City of Marion. Half of the area was dedicated to a driver school, and that
was 80 per cent bitumen roads—the old driver school on Oaklands Road. This
project—it was driven by some state agencies and the federal funding that gave
it the catalyst to go ahead—converted that park from a driving school,
basically mainly bitumen, into a community asset as well as a feature treatment
wetland. It had multiple inputs from design disciplines, and it provided green
infrastructure to the residents as well as being a stormwater-harvesting
facility. When you go there at a weekend and there are kids running around, the
average pundit would not know that it is an active stormwater-harvesting
system. It is harvesting the water and storing it underground, and the water is
then plumbed to 30 reserves around the City of Marion.
Dr Peter Coombes discussed the Wannon water harvesting scheme in
Victoria, where water is harvested from roofs into centralised supply (a dam).
Dr Coombes stated that the project 'is far more efficient than their water
supply catchment, so it is drought-proofing their area' and emphasised how the
scheme is cost-effective:
...the full cost of their roof water harvesting scheme, without
carrying in any of the stormwater benefits—just the water supply—was under
$2,000 a megalitre. This is under $2 a kilolitre, which was cheaper than their
mains water supply.
Large-scale schemes in other countries were also noted—Stormwater
Australia advised that in Singapore, all stormwater can be collected and used
for potable water supply.
Views on stormwater harvesting
As has been already noted in this report, the volume of stormwater in
Australian cities is similar to, and in some cases exceeds, the volume of other
types of water used. It follows that stormwater harvesting could provide
another source of water for cities. For example, the CSIRO stated that
stormwater harvesting has 'proven potential to meet large urban water demand'
with added environmental benefits, such as improved coastal water quality and
lower greenhouse gas emissions 'relative to alternative more engineered
The Waterway Ecosystem Research Group argued that stormwater harvesting
stores did not need to be very large 'to achieve a supply reliability
comparable to that achieved by large water supply dams'. It explained:
...a storage volume of 25 litres per square metre of roof
(equivalent to 5000–6000-litre storage for an average house) or road area would
retain 99.6% of runoff, in Melbourne if there were sufficient demand (as would
be achieved, for instance, by plumbing roof-top tanks on a multi-storey
building into all of the building's toilets, or by directing the runoff to a treatment
system for augmentation of the potable water supply). Such a harvesting system
would greatly reduce the cost and area required for infiltration systems that
are required to retain and treat unharvested runoff, to restore lost baseflows.
If such systems were applied to every roof of Melbourne, they would supply 60%
of Melbourne's total water demand.
Stormwater harvesting projects have been encouraged by Commonwealth
funding (discussed in Chapter 5) and state government policies. Water Sensitive
SA, for example, advised that the 2011 South Australian State Strategic Plan
has set a targeted for up to 35 gigalitres of stormwater to be harvested each
year by 2025. In 2008–09, the state's recycled stormwater harvesting
capacity was 5.8 gigalitres per year; after the completion of various
stormwater harvesting and reuse projects, by June 2014 capacity had increased
to 22.7 gigalitres.
The Adelaide and Mount Lofty Ranges Natural Resources Management Board
submitted that harvesting needs to be supported by a greater array of
management practices and policies so that it can meet the challenges unmanaged
stormwater presents to urban and natural environments.
The CSIRO suggested that stormwater harvesting should be undertaken on a
'fit for purpose basis', with a view to using stormwater where low quality
water is suitable. For example, the CSIRO observed that high quality drinking
water is not needed for greenspace irrigation. Such action would 'improve the resilience
of the water supply system', by:
...providing a buffer against increasing urban demand from a
growing population and increased uncertainty in future inflows to drinking
water catchments due to climate variability.
Potable or non-potable use?
An issue that divided stakeholders is whether the aim of stormwater
harvesting should be to provide water for potable or non-potable use.
Mr Adam Lovell, Executive Director, Water Services Association of
Australia (WSAA), expressed his view that 'stormwater recycling is more in the
non‑potable, liveable city type domain'. He noted that, at present, he
was aware of only one project in Australia that is considering stormwater
recycling for potable use.
Dr Peter Coombes, however, suggested that stormwater could be used for
potable supply in a cost-effective way, and that the technology and ability to
do this exists. He explained:
I was a judge in the Victorian
stormwater industry awards. Without naming the consortium, they presented, in
an area to the west, harvesting the stormwater where it is and injecting it
straight into the existing distribution system...If you are treating it,
obviously you are eliminating those health risks. We treat mains water with a
multibarrier approach. If we did not treat mains water, there would be health
risks also. We seem to forget that we treat mains water from catchments. If we
are treating some other water, we would obviously treat it to the same health
requirements—and yes we can do it. We have been able to do it for nearly 30 years...The
point is that if you did that, because you were backed up from other water
sources, you do not need big storages. You are injecting straight into the
distribution system at opportune places, with treatment. Obviously you are
trading off the economies of the right scale to do it.
Under this model of stormwater management, Dr Coombes observed that
'it does not have to rain all the time'. Dr Coombes added that the use of
stormwater in this way presents 'very strong economic benefits' as the water
management that is occurring within the catchment manages run-off and flooding,
but also allows more water in the large dams to be saved for use during a drier
Stakeholders, however, identified challenges about the use of stormwater
for potable supply. One of the key challenges that would need to be overcome is
perceptions about water treatment. Dr Peter Coombes recalled that when he was the
Chief Scientist at the Office of Living Victoria and stormwater harvesting for
potable purposes was first proposed, 'the health department got very upset'. He
There was this absolute assumption that if it is reticulated
water, mains water, or whatever you want to call it, it is magically okay, and
any other water can never get to that standard. That is nonsense. I heard on
the ABC the other day that some of my colleagues that are in WSAA are saying it
is okay to drink wastewater. Yes it is, because we have to treat it to the
point where it is okay.
Mr Naumann from the City of Salisbury made a similar observation about
the ability to treat stormwater in a cost-effective way and acknowledged that, despite
this, there is 'fear in the community about getting recycled water into
drinking water'. Mr Naumann commented:
We can already treat stormwater for less than $2 a kilolitre.
We can get it to the drinking water standard needed but the public are not
ready for it yet. The focus groups we have had are not ready for it. Whenever
we put up a new project, people come to us and say, 'Hey, I hope you're not
doing that into our drinking water.'
Mr Naumann added that SA Water and the Department of Health refuse to
let recycled water 'anywhere near the drinking water networks'. He explained
that the principal concern is that at the moment 'millions of dollars' are
spent monitoring water quality in a system where all water is brought through
one quality assurance point.
Mr Naumann explained:
It is really about controlling the risk and that is what SA
Water and the department of health are quite rightly concerned about. That is
where we have to be a little bit careful of just charging ahead and putting
recycled water back into the networks. I think it is a worthwhile target. I
think we should be setting a framework or a time frame of saying that 10 or 15
years out we would like to have a deregulated drinking water network and then
look at how we go about getting there over that time frame.
Mr Naumann suggested that the recycled water networks built in Salisbury
provide 'a chance to practice, to get things right, to get the community's
confidence up to know that the private operators who will deliver cost savings
in the long run are good enough to deliver drinking water'.
Mr Andrew King, Chair, Stormwater South Australia, noted that 'research
into the ability to take stormwater for potable use suddenly opens the
marketplace up in terms of what that water can be used for'. However, he also
highlighted that the supply of stormwater for potable use presents a
distribution problem in getting the harvested stormwater to the user. He
A lot of the schemes that have been built to date have taken
the opportunity of that connectivity between location of harvest and ability to
harvest and close-proximity utilisation of that by building their own small
networks for distribution. Taking water to potable opens up the practicality of
being able to then utilise existing water distribution networks, removing any
legislative issues about tapping into in the South Australian environment the
SA Water network. As soon as you get a greater market for that and that
technology and the reassurance of being able to take stormwater to potable the
pricing will come down.
Dr Robin Allison, who also represented Stormwater South Australia at the
committee's Adelaide hearing, suggested that indirect potable reuse 'may be
feasible in terms of bulk stormwater feeding into reservoirs and then shared
treatment and further infrastructure'; that is, the stormwater would be sold to
the water utility who would then treat and supply it using existing practices.
Dr Allison concluded:
I think we are a fair way from going directly from a
stormwater harvest site into the mains network. I think that is a bigger step
than the indirect process...[b]ecause of the quality controls required and the
number of people handling at changeover.
Need to find demand for stormwater
Regardless of whether the objective is for stormwater to have a potable
or non-potable use, several submitters concluded that for stormwater harvesting
efforts to expand, a greater demand for stormwater is needed.
To meet the South Australian Government's target of 35 gigalitres of
annual stormwater harvesting by 2025, Water Sensitive SA argued that
'greater emphasis now needs to be placed on developing the customer/end user
base and driving demand'. Water Sensitive SA considers that in South Australia,
a 'lack of distribution networks and water pricing policy across all water
sources (potable water, River Murray allocations or groundwater resources) is
limiting demand for treated stormwater'.
The CSIRO noted that uptake of stormwater harvesting 'has been slow to
date'. The CSIRO's submission suggested that 'the encouragement of the use
of additional demonstration projects may assist to gain public and regulator
confidence' in stormwater.
The Waterway Ecosystem Research Group noted that stormwater harvesting
and treatment to provide potable water was one option to increase demand for
stormwater, thereby protecting receiving waters from polluted urban stormwater.
However, other options include:
urban planning that ensures 'high-demand non-potable uses (e.g.
agriculture, water-using industries) are placed closed to urban areas'; or
ensuring that 'sufficient areas of vegetation are retained in the
urban landscape...to maintain pre‑development evapotranspiration rates, and
urban stormwater runoff is directed to these vegetated areas'.
The need to find additional demand for stormwater was effectively
demonstrated by the experience of existing stormwater projects. Although the
committee was provided with examples of successful stormwater harvesting
projects, the committee also was told that there were difficulties in expanding
these projects. Mr Naumann told the committee that the stormwater harvesting
projects in Salisbury harvested three gigalitres in 2014. The existing projects
'could potentially be harvesting up to eight gigalitres', however, as only 2.5
gigalitres were sold in 2014, harvesting has been 'cut back because it costs
money to harvest...So we only harvest what we need'.
Nevertheless, opportunities for expansion are being considered.
Mr Naumann advised that research from the CSIRO is assisting Salisbury
Water to focus on industrial companies that need water of a higher standard
than drinking water, which the companies are currently obtaining from the main
water supply and treating further before use.
Mr Naumann also suggested that an expansion of the City of Salisbury's network
into neighbouring council areas 'that have not had either the initiative or the
opportunity to get the funding that we have had' would allow for growth,
although additional funding would likely be needed to accelerate this process.
Mr Naumann added:
If we really wanted to take another big leap forward, and I
think we are ready for that, we need about $15 million to link all of the
different little council networks around the place. It has also been touched on
before that the risk with stormwater is that we go into another period of
drought. Stormwater is notoriously unreliable. We found in the previous
seven-year drought that Adelaide went through that we got caught out in a
couple of our schemes where they were not large enough to support the customer
base that we had, so we scrambled to connect them.
Another barrier to the increased utilisation of stormwater is potential
'competition' from recycled wastewater, as 'the combined volume of the two
resources will far exceed the likely demand for water in a given area'.
However, some stakeholders considered that stormwater could be used in
conjunction with wastewater. Ms Mellissa Bradley from Water Sensitive SA
suggested that there are opportunities to mix stormwater and wastewater in some
projects, as 'the salinity of wastewater is high and stormwater can be added to
the supply to dilute the salinity'.
Mr Bruce Naumann from the City of Salisbury observed that if stormwater schemes
within a city were linked together to form a city-wide network for non-potable
use of stormwater to green schools and reserves, the wastewater could be used
in that network. Mr Naumann concluded that the use of wastewater in this way
would be 'a great opportunity to maximise the use of stormwater and waste
water and get it back into the suburbs'.
Water sensitive urban design and water sensitive cities
As outlined in Chapter 2, one of the benefits of stormwater put to the
committee is that stormwater projects can help make cities 'more liveable'. In
relation to this, several submissions referred to the concepts of water sensitive
urban design (WSUD) and water sensitive cities. WSUD involves the integration
of the urban water cycle, such as water supply, stormwater and wastewater, into
urban planning processes. WSUD projects use vegetated stormwater treatment
examples of which include bioretention swales, wetlands and raingardens in
urban residential developments.
In addition to improved water management, WSUD can provide other benefits, such
as the creation of recreational spaces.
Water sensitive cities combine elements such as WSUD with social
systems. Water sensitive cities:
...interact with the urban hydrological cycle in ways that:
provide the water security
essential for economic prosperity through efficient use of the diversity of
water resources available;
enhance and protect the health of
watercourses and wetlands;
mitigate flood risk and damage;
create public spaces that harvest,
clean, and recycle water.
An example of urban planning that presented challenges for WSUD
principles was outlined to the committee. Ms Mellissa Bradley, Program Manager,
Water Sensitive SA, referred to two local government areas within Adelaide
where impervious surfaces account for 65 per cent of the total surface area.
With additional development planned over the next 30 years, the amount of
impervious area in the council districts is expected to increase to
approximately 89 per cent. Ms Bradley stated:
You are talking about 10 per cent of a whole council area,
left, that is not impervious. That means we will have to be extremely clever to
get those liveable outcomes for the people who live in those areas so that they
do not become big, hot heat islands with no amenities.
I drive down some of those suburbs that have already been
converted and I feel for the people who reside there. For our image
galleries, our website, I am trying to take photos of good practice
water-sensitive urban design and where it can be improved, and I feel that some
suburbs are struggling from becoming highly impervious heated areas.
Water-sensitive urban design can do a lot to mitigate that...[and stormwater] is
absolutely integral to that.
eWater argued that all government authorities should recognise the value
of WSUD principles and adopt these principles in land and infrastructure
development codes. According to eWater, nationally consistent WSUD guidelines
should be developed that aim to provide 'a nationally consistent approach for
managing stormwater in an integrated way'.
...the full and consistent implementation of WSUD practices are
limited to only a handful of large and/or innovative local government
authorities. The problem seems to be that most councils don't have the
human or financial resources to implement WSUD principles even if they want to.
A broader recognition and funding of WSUD practices across all stormwater
management authorities is essential.
Stormwater Victoria referred to innovative WSUD projects in Melbourne,
however, it emphasised that ongoing support for innovation is critical. It
Water sensitive urban design is less than 20 years old and
has yet to reach full maturity as a discipline. The industry has noted a
decline in recent years for the support of research as industry and government
budgets tighten. Stormwater Victoria sees this as a potential issue as without
innovation and scientific research further progress will be hampered.
The Australian Academy of Technological Sciences and Engineering (ATSE)
argued that Australia needs to 'further develop its vegetated stormwater
harvesting technologies, as they currently lag far behind other water treatment
technologies'. The ATSE further argued that ongoing investments to
implement stormwater WSUD technologies 'will ensure that we can delay
augmentation of existing drainage infrastructure, making considerable savings'.
Other issues affecting the widespread adoption of WSUD that the
committee was informed of include:
lack of willingness from developers;
insufficient project experience in WSUD—Water Sensitive SA
submitted that, in Adelaide, knowledge about WSUD projects is 'confined to a
limited number of individuals and organisations' and there are relatively few
examples in Adelaide that can be used for training and other educational uses;
a lack of awareness and application of existing WSUD technical
guidelines—this was highlighted as an issue in South Australia.
Limits to stormwater harvesting and alternative options
Although witnesses were generally optimistic about the potential for
stormwater to be better managed and utilised to a greater extent, some of the
evidence received by the committee recognised potential limits to the use of
stormwater. This section considers this evidence.
Mr Adam Lovell, Executive Director, WSAA, suggested that stormwater and
rainwater can contribute to the water supply of a city, 'but it is certainly
not going to save a city'. To demonstrate this point, Mr Lovell used the
water demand of Sydney:
Sydney has, in a drought year, a 500-gigalitre-per-year
demand. In a normal year it is 600 gigalitres per year. If you put a
five-kilolitre rainwater tank in every household and you have them operating
for the toilet, the washing machine and things like that—operating absolutely
optimally—the best you could get would be 70 gigalitres per year—10 to 15 per
cent of supply.
Mr Lovell also noted that the demand and supply for stormwater may not
match up. He observed that 'industry needs to operate 24/7 and customers need
water 24/7, but it might not rain for three months'.
Mr Lovell also drew attention to the large storage spaces that are needed for
water supply. He explained:
The biggest problem we find in urban areas is that people
just do not understand the size of storage required. All this water is going
down the drain, but they do not realise there is another drain down there and
another one down there—and all of a sudden you need Sydney Football Stadium
sized storage for one rain event. We all know that that is not possible—the
cost and the use of that. And then you have got to store and treat it. 
Mr Lovell concluded that, because of these considerations, it 'is really
important to say: what do we actually want?'. In this regard, Mr Lovell
highlighted the 'fantastic opportunities' that stormwater presents for
contained projects that relate to liveable cities and parks. Mr Lovell uses the
Central Park development near Central Railway Station in Sydney as a an
It has beautiful green walls coming down. There is a big
capital uplift. People pay a green premium. They are pulling stormwater off
that site and recycling it on site. That is the type of disruption and
innovation we are seeing. And that is not being provided by Sydney Water. I am
not speaking on behalf of them. It is provided by the private sector, through
innovation. I think that is a fantastic thing.
Submitters also suggested that some of the pollution from stormwater
could be addressed directly at the source. The Australasian Chapter of the
International Erosion Control Association (IECA) argued that greater funding
and resources should be given to addressing the pollutants in stormwater linked
to the construction sites as 'managing stormwater quality during construction
is cheaper (per kg of pollution) than during the operational phase of
development and has far greater potential for large‑scale catchment
Stormwater as a substitute for
Another matter examined during this inquiry is the implications for
stormwater use of investments made in desalination plants. In particular,
stakeholders considered whether stormwater can be a substitute for
desalination, or whether desalination capacity is required regardless.
The CSIRO noted that stormwater harvesting could replace other sources
of water that supplement traditional supplies, such as desalination plants. The
Previous reliance on desalination plants over other
alternative water sources, such as stormwater harvesting has increased energy
use in the urban water cycle...with associated implications to greenhouse gas
[H]arvesting of stormwater for local uses has the potential
to reduce greenhouse gas emissions associated with alternative sources which
involve intensive pumping to transfer water across large metropolitan areas.
Mr Andrew Allan from Stormwater Australia suggested that 'some of the
desalination type investments have been justified on the need to have a
rainfall‑independent source of water'. Mr Allan observed that this
applies in 'a traditional catchment-type water source where, when it rains,
water soaks into the soil and the trees evapo-transpire it'. He argued,
however, that in the urban environment the rainwater does not disappear; rather,
rain that falls on hard surfaces becomes an 'efficient way of generating
run-off'. Mr Allan concluded that stormwater 'generates problems but also
Some downsides of desalination were highlighted. In particular, the
committee received evidence about the limitations and costs of operating a
desalination plant. For example, Mr Pfleiderer from Stormwater Victoria
discussed the 'shadow cost' associated with a desalination plant:
Once you do turn it on, the cost of that water is pretty
high, much higher than what you are paying for out of your tap, so if that is
actually recognised then stormwater does become quite competitive, rather than
just fixing on that dollar per kilolitre that you have on your water bill.
Witnesses also observed that desalination plants do not assist with
flood mitigation, urban heat islands, or addressing environmental degradation.
It was further noted that the process of desalinating seawater is energy
intensive; although stormwater has pollutants that need to be extracted, representatives
of Stormwater Australia and Stormwater Victoria argued that salt is the most
challenging substance to extract.
Whether stormwater could be used at a lower cost than desalination was
explored. In regions where managed aquifer recharge is possible, such as
Adelaide and Perth, Professor Ana Deletic referred to a trial that is examining
the injection of treated stormwater into the aquifer for access downstream in
subsequent years. Professor Deletic indicated that such activities should not
incur significant costs.
Some witnesses were asked whether the significant investment made in
desalination created an incentive for the owner of the desalination plant to
resist large‑scale stormwater projects to ensure that their investment
will be financially viable. Mr Allan provided the following response to
Just thinking this through: there is only so much money in
the system, so there is a need to look at what money has been spent on. Those
desalination type options were put in during the drought years towards the end:
'Okay, we're running out of water. We need a really quick fix. This is the
insurance policy that we can buy.' Depending on where you are, they cost more
or less to build.
Mr Allan added:
We now find, as we are coming
out of the drought, that we have those plants there. They are not being used,
largely, because we do not need them because it is raining and the dams are
filling up and everything, but we have to pay for them. I think what happened
in the past was that we got a solution, and then people forgot that we almost
ran out of water and you have to pay back what you have bought. I think we are
in that paradigm now.
Professor Tony Wong from the CRC for Water Sensitive Cities, however, disagreed
with the argument that capital investment in desalination has negative
implications for stormwater harvesting investment. Professor Wong countered
that desalination plants provide a safety net that allows for innovation. He
A lot of the innovation that the CRC for Water Sensitive
Cities is developing, fostering and creating adoption for is very sustainable
solutions with a very long incubation period simply because of the need for us
to diffuse that solution. The long incubation period in the past has been the
key impediment to any uptake of innovation in this area because in a crisis you
cannot deliver some of those solutions. The desalination plants—certainly in
Melbourne—have given us an era of stability in terms of our resilience to drought
at least for the next 25 to 30 years. It gives us the opportunity to deliver
much more innovative solutions and to incubate that before we get to the
30-year useful life of the current desal. The aim is not to have to build
another desal plant rather than to not build the first one. The first one is a
foundation, a safety net for innovation.
Mr Adam Lovell of the WSAA argued that desalination and stormwater need
to be considered separately. He provided the following reasoning:
First of all, for the capital cities that have desalination,
it is an insurance policy they are in. They are properly priced. Some of them
received government funding and some of them did not. For instance, Sydney
Water's desalination plant has been sold to the private sector. Sydney Water
does not have control over the operating procedures of that plant. That is not
Sydney Water's call; that is the call of the government, which says when that
desal plant can be turned on. Utilities do not overall have control about
whether stormwater should or should not be part of the diverse range of sources
available for potable supply. Desal is climate independent potable supply, very
clearly. I think stormwater recycling is more in the non‑potable, livable
city type domain. There is only one instance that I know of, Kalkallo,
just north of Melbourne, that is looking at it from a potable use scenario.
Despite some disagreement between stakeholders about the implications
presented by existing desalination investment, there was general agreement that
long‑term changes would necessitate the consideration of greater
investment in stormwater harvesting. For example, Mr Allan considered that
population growth and climate change requires that consideration be given to
the water that could be harvested from stormwater. He told the committee:
...if we were smart about things going forward, we have these
investments now and they are going to have to be paid back, but some of the
modelling that has been done suggests that with population growth and with climate
change we are probably going to find that we need to build another desal plant
or something else into the future, so we should be making those co‑investments,
smaller over a longer period of time, that are actually going to help us out. I
think they are a reality of the landscape, but they are also competing for a
scarce resource, and, moving forward, we need to be investing more in a
stormwater fix for a whole range of other reasons which are not just water
Need for better data, guidelines, planning and training
Submissions called for studies and guidelines on various matters to
support better stormwater management outcomes.
Although detailed flood studies have been undertaken, the CSIRO noted
that additional data on stormwater quality and capturability, as well as
further research on the environmental impacts, costs and benefits associated
with stormwater and stormwater harvesting may be needed.
The CSIRO stated that an impediment to the adoption of scientific advances is 'the
lack of sufficient data for an effective cost‑benefit analysis on the
value of capturing and reusing stormwater compared to other potential water
sources'. In particular, the CSIRO noted that there is insufficient information
'on the value to the environment and social amenities for reducing the
stormwater flows in urban creeks and drains'.
The current approach to assessing the costs and benefits of different
stormwater management approaches was an issue raised by several submitters. Mr Adam
Lovell told the committee that 'the biggest problem in stormwater is: who
benefits and who pays'. He explained that the answer to this question is:
...easy in a water utility provision, because you are providing
drinking water and you know exactly who is getting it and you know exactly who
pays for it, in water and waste-water services. Stormwater is different. The
beautiful parks and gardens of Adelaide or downtown Sydney or Brisbane—those
are for the benefit of all. But they come from good stormwater management. So I
think that that is where the community cost becomes really important in terms
of how you would enable innovation.
Mr Lovell argued that consideration of cost 'should be on the basis of
total community cost, not on the cost to the individual entities that are
involved in delivering that stormwater program'.
The CRC for Water Sensitive Cities hinted at the difficulty in fully
considering the liveability of a city based on the current measurement of
economic benefits that could arise from stormwater management. The CRC
The economic benefits of innovation in stormwater management
are poorly and narrowly defined. The notion of 'liveability' has wide ranging
connections to the economy of a city and it is necessary to have these
benefits, many of which are non-market benefits, understood and quantified.
The CRC for Water Sensitive Cities outlined other potential costs that
are not currently taken into account or are difficult to monetise, although
some of these costs can be quantified. The matters highlighted by the CRC
health costs related to urban heat effects;
'system resilience', which 'has intrinsic economic value that
could be quantified through a combination of real option analysis for water
security, flood management and aquatic ecosystem health in combination with
increased biodiversity and ecological health of the aquatic
improved 'physiological health and recovery of people that are
more connected with green space and being more physical active (such as walking
through green corridors in their suburbs)'.
Dr Peter Coombes argued that the future costs have not been taken into
account adequately. Dr Coombes suggested that the centralised nature of water
supply will lead to higher costs. He explained:
...there have been substantial
increases in operating costs of our major urban utilities versus other
utilities that have more distributed solutions where their operating costs have
not grown. Operating costs are not really counted in these processes. So, some
of the things that we are not counting are costing us billions of dollars a
Dr Coombes also argued that better performance data could lead to
improved outcomes. Dr Coombes called for the creation of a national monitoring
program and reporting agency for urban water and stormwater issues. This agency
would provide 'annual reports on the status of water cycle resources (including
stormwater), forward plans and policies, facilitate monitoring of urban
catchments and arbitration on the decisions about innovation'.
In support of this recommendation, Dr Coombes remarked:
One of the best things that happened in water management in
Australia was the provision of a national performance report for our urban
utilities. That then allowed things to be compared and contrasted. It also
allowed federal and state governments to more fully understand where they
stood, the status of the resource, the economic situation they were in and so
The CSIRO suggested that a centralised repository of data on water
source, supply, discharge, and quality, such as a 'water bank', could improve
future decision‑making on water infrastructure investments.
Better networks between stormwater organisations, researchers and
project developers could also yield benefits. Ms Mellissa Bradley, Program
Manager, Water Sensitive SA, told the committee that:
While we are working in an informal manner together, across
state based capacity within programs, it would be advantageous if we could have
some national cohesion. It might save our limited funds, because we are all
struggling financially, to get better consistencies and efficiencies.
Ms Mellissa Bradley added that her organisation considers that:
...continued and expanded effort is required to bring research
learning to practitioners who need to apply these learnings. The state based
capacity‑building programs for water-sensitive urban design are an
excellent conduit to bring these research outcomes to practitioners and can add
value to research adoption pathways, because we feel there is a lot of research
going on but it is not actually getting out to the people who need it, and we
can see that there are opportunities there.
Matters regarding planning and training were also noted. These included:
Water security—given the potential contribution stormwater could
make to a diversified water supply and, therefore, water security, it was
argued that water authorities should conduct detailed risk assessments and
environmental impact assessments on water security. The studies would focus on
the costs and benefits associated with using stormwater for potable purposes.
Training—the Institute of Public Works Engineering Australasia
(NSW Division) suggested that operational staff need upgraded skills.
The Institute observed that it 'is easy to understand how a pipe works,
but understanding how a bio retention basin works is a whole different ball
game'. Further, the Institute argued that stormwater projects should be kept
simple as 'if you need a degree to understand how it works, it will not be
operated or maintained properly or cheaply'.
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