Does the World Need Desalination?

Water is humankind's most precious resource. Demand is rising and resources are running low. Conservation and reclamation are needed all over the world. Water shortages in the Middle East, Australia and the Western United States are creating an appetite for new water supplies. Greater efficiency and re-use of water that's now being wasted are obvious fixes. Beyond that, there's desalination of ocean water to create new supplies. That takes expensive technology. Will it discourage conservation? Is it worth the energy it demands and the impact on the environment?  We look at the available options to cope with an inevitable, worldwide crisis.