Water scarcity, potential alternative sources and treatment feasibility

With ever-increasing population and impacts of climate change, water supply systems in many cities of the world are under tremendous stress. Water authorities in many major cities around the world are struggling to maintain required water demand. Available potable water supply is crucial in some mega cities within developing and poor countries. Developed nations with ample resources and wealth are managing their demands to a satisfactory level, however still facing challenge to tackle demands. As such, water authorities are adopting several measures including demand management and identifying alternative water sources such as stormwater harvesting, greywater and wastewater reuse and desalination. During a decade long (2003~2012) drought in Australia, government spent 18 billion dollars to construct several desalination plants, most of those are now sitting idle as the climate has reversed with ample rains, which sufficiently contributing to the water supply reservoirs to fulfill the demands.