Diversifying our water supply system: meeting Melbourne’s needs locally
Posted in Opinion by Kate Archdeacon on November 20th, 2009
From “A land of droughts and flooding rains: it is time we adapt to this reality” by Anjali Brown, Water Policy Manager ATA
The single most commonly used rationale for the Wonthaggi desalination plant has been the fact that we do not have enough rainfall. A lesser quoted fact is that even in years of drought, 400-500 Gigalitres of rain falls on Melbourne, only to be lost down stormwater drains and flushed out, via our waterways, into Port Philip Bay.
500 gigalitres is more than the city’s total water use and it is double the amount the desalination plant, at maximum capacity, can produce. We cannot and should not be misled by the low rainfall argument or that desalination is our only option. Desalination is a last resort in a long line of alternative technologies that, if implemented, would go much further to securing our water supply. Climate change has reminded us that we live in a country of droughts and flooding rains. In order to respond to these weather patterns, Victorians require a diversity of options. In an uncertain climate, having a range of options is a strength: if one fails there are multiple back-ups.
A crucial area to improve is what happens in the home. Householders with a variety of water supply sources are less vulnerable to the extremes of drought or flood than those who rely solely on the mains water network. This is not simply because they have multiple sources to fall back on in case one goes bad or becomes too expensive, it is also because the experience of using water wisely in the home increases the householder’s understanding of and control over their water supply. In a recent study completed by the Alternative Technology Association, householders who installed greywater systems found their wasteful water habits changed dramatically. They became more aware of what the weather was doing and used their water system accordingly. As their awareness increased, householders relied less and less on mains water. Diversity of household water supply options is key to our water security.
When the 400-500 Gigalitres of rainwater falls on Melbourne, we need domestic stormwater infrastructure to capture rather than dispose of this rainwater. It is estimated that the same amount of water as the desalination plant will produce could be saved if just 25 per cent of Victorian households had a small 2000 – 3000 litre rainwater tank supplying the toilet, laundry and garden. Some of the rainfall can also be intelligently diverted to wetlands which help reduce the impact of flooding, improve river health and act as natural water storage systems.
Also misleading is the idea that if we do not choose desalinated water, we must drink recycled water. While the technology is there to provide safe recycled drinking water, Victorian is not yet at a stage where we must drink recycled water. Drinking water and food preparation accounts for only 5 per cent of household water use. Our reservoirs can supply this 5 per cent. The other 95 per cent need not come from reservoirs, rural areas or unsustainable sources like desalination. Safely recycled water can be reused around the home for toilets, laundry and gardens. ATA research found that greywater recycling can reduce mains water use by 33 per cent, and in some cases, more. It is true that pumping recycled water long distances from treatment plants is energy intensive, so the key here is for households and communities to be supported to install small-scale, onsite wastewater recycling systems. Designing urban landscaping to trap and filter water also helps green suburbs, creating cooler moister environments which limit the effects of drought.
Diversifying our water supply system is an opportunity for Victorians to adapt to a land of bushfires and floods without the necessity of high water bills and without leaving them reliant on short-term unsustainable supply options like dams and desalination.
Billions are being spent on a desalination plant that will run for just 25 years, hardly ensuring the water supply of one generation, never mind future generations. To provide Victoria with greater water security, money would be better invested in water technologies that will create a fundamental shift in our understanding of water use by allowing householders greater access to and control over their water. We live in a land of extremes. By using technology to help us adapt and harness the water resources we have rather than further damaging our environment with unsustainable end of the line solutions, we can protect our own and future generations’ right to affordable water.
Read the full article by Anjali Brown.