Over at Columbia University’s “Water Matters”, Debbie Cook has been making the case against desalination as a water supply solution. She has a number of lines of argument, but it all boils down (pardon the pun) to cost, and to a series of societal tradeoffs that flow from that. Consider Saudi Arabia’s decision to use its plentiful energy resources to provide desalinated drinking water:

According to some reports, water rates in Saudi Arabia cover less than half of one percent of the cost of producing desalinated water. Subsidizing water, food, and gasoline is seen as a way of sharing the country?s oil wealth. But the absence of any price signal has led to some of the highest per capita water consumption in the world, and highest greenhouse gas emissions in the world. Saudi Arabia now ranks 6th in greenhouse gas emissions, half directly attributable to desalination. Authorities are straining under the burden of water and energy demands pushed by burgeoning population growth. Despite allocating $150 billion over the next five years for power and water projects, they have been forced to abandon their goal of becoming self-sufficient in wheat production. With natural gas in short supply, the feedstock to produce electricity will continue to be oil. The irony is that oil revenues make up 90% of the Saudi government?s budget so every barrel diverted to water is a barrel that cannot be sold on the market to fill state coffers.

More of Cook’s desal arguments here and here.