What is fresh water? Don't be too quick to say it's a precious natural resource. To me fresh water is energy. There is heaps of water on earth it may just not be where or in the form that you want it at the time that you want it. You will get fresh water anywhere you want it in any quantity if you are willing to provide the energy and infrastructure to get it there. To me energy and infrastructure are fairly similar too as infrastructure is produced at its source by energy.
When we look at conventional forms of water supply consisting of dams and piping systems we don't see the huge energy costs involved or the massive environmental damage caused by these schemes. The biomass destroyed in the flooding on the valleys upstream of the dams alone adds millions of tonnes of green house gases to the atmosphere.
Building the associated dams and infrastructure utilise massive resources in the construction and manufacture of the component parts. Once operational we then forget about the massive pumping that has to be undertaken to get the water to the point of supply at the pressure we want to use it at. In many cases the electrical usage of present systems rival that of desalination systems. For example Sydney Water has always been one of the biggest users of electricity in the state of NSW.
As such I see desalination plants as an undervalued solution to at the least the drinking water needs of this country. As the efficiency of these plants increases with technological developments and as the supply of green energy increases I see desalination plants being a long term solution to the water supply issues of this country. I also look forward to a time when green energy and desalination plants can result in the decommissioning of many of the dams (both hydro and water supply) built in sensitive environmental areas such as Lake Pedder, the Snowy mountains and Warragamba. Returning these areas to nature will also recreate these places as the large carbon sinks that they once were.
Unfortunately one of the draw back is that a lack of water has always been regarded as the reason this country can't sustain many more people than we have currently. Desalination plants take away this natural constraint. I see a great deal of environmental damage done to this country (and the world in terms of Australia's growing Carbon footprint) as a result of Australia's ever increasing population. It is hoped that we can take stock as a nation and stabilize our population despite the fact that the water supply issue is no longer the population constraint that it once was.