Freshwater is the most fundamental natural resource. But its sources are fast dwindling or becoming contaminated throughout the world. At the start of the 21st century, nine countries with around 35 per cent of the world population were believed to have less than 2,000 cubic metres of renewable freshwater available per capita per year. This implied acute water scarcity. Nations in this list included India, Nigeria, Kenya and China. The situation has worsened over the years with water quality deteriorating due to unabated sewage discharge. This crisis can be averted by using technologies that offer potential for improving efficient use of freshwater.