Desalination Compared To The Alternatives

Rain is the cheapest, cleanest and most efficient source of fresh water. Problems arise when rain patterns change or people live where there isn't enough rain. Australia now suffers from both problems.

Australia has a growing population. Even if everyone cuts back on individual water use, overall water consumption will grow due merely to force of numbers. While huge efficiencies can be reaped in agriculture, agriculture is a important part of the Australian economy and its regional social fabric. It can only be squeezed so far through allocation cutbacks and higher water prices without aggravating other problems such as urban migration and a worsened national trade balance.

In urban areas, dams can hold water. But evaporation, changing rainfall patterns and the big environmental footprint dams create may well consign them to the category of "yesterday's solution." Other ideas involve pumping water from where rivers are to where the people are. For instance, Libya has its Great Manmade Canal bringing water from the south of the country to the heavily populated north. California draws water from the Colorado River to slake thirsty Los Angeles. Western Australia and Queensland have both considered lengthy pipelines to carry water from wetter northern areas to drier southern areas. For its part, Sydney has considered pulling water northward from the Shoalhaven River.

Apart from more rain or more dams, other alternatives range from desalination to rainwater tanks. Lined up side by side with the others, desalination doesn't come out so badly. In a November 2006 study compiled for the Prime Minister and Cabinet, Australia's major city water choices -- and their prices -- were laid out in the table chart below.

Source: "Securing Australia’s Urban Water Supplies: Opportunities and Impediments," Department of the Prime Minister and Cabinet, November 2006, page 9

The attractiveness of desalination for South Australia, and particularly the Upper Spencer Gulf is that solar energy can be used and that desalinated water can replace Murray River supplies. This creates energy and water savings. To give an idea of some of the relative costs involved, pumping Murray River water to Adelaide's reservoirs costs roughly 65-75 cents per kilolitre before water treatment costs are taken into account.