The role of technology in achieving water security.

The development of technologies for the provision of clean and plentiful supplies of freshwater has been a central feature of successful civilizations. In advanced economies, we have grown to assume that the tap at home will always provide as much as we want of clean drinking water. Rapid economic development and population growth globally, in particular in cities, are hugely expanding expectations for modern water services. Ageing assets and a changing climate mean that even mature economies with a huge stock of water infrastructure face substantial challenges. These challenges can only be met by a change in behaviour, better infrastructure, improving efficiency of current technologies and the development of completely new technologies. For instance, the established use of drinking water to flush toilets, water gardens and wash cars is not a sensible use of vital resources, including energy. The future will require technological innovation, improved thinking about the exploitation of water supplies and better incorporation of new technologies into current and future infrastructure. We are fortunate in the UK and most of the developed world in being secure in the knowledge that our domestic water supplies are safe to use and consume. Effective regulation and established technologies ensure that instances of microbial pathogens and chemical contaminants entering our water supplies are rare. In this regard, we still owe an enormous debt of gratitude to the civil engineers, most notably Joseph Bazalgette, who in the 1860s designed and constructed the water treatment system, which is still the blueprint for many parts of the world. It is this infrastructure that the Victorians put in place that we still largely rely on to ensure that wastewater is effectively treated and recycled. Indeed, the technology has changed little since those pioneering days. However, the rapidly expanding global population and its tendency to concentrate in mega-cities are putting untold pressure on sewage processing and all aspects of current water treatment systems, which after all