Developing new sources of fresh water can help to meet the needs of populations and industries in areas where traditional sources cannot meet the growing demand. Although increased water efficiency and conservation can go a long way, existing fresh water resources cannot adequately meet demand in arid parts of the world (especially in large cities).
Treating wastewater for reuse is the most energy-efficient way of reclaiming water for consumption. However, advances in seawater desalination over the past decade have made this technology another viable fresh water source. Desalination plants can today produce fresh water at an average cost of approximately 0.7 USD/m3, meaning it would only cost around 3.5 US cents per day to provide one person with the WHO recommended daily minimum of 49 litres of clean water. Currently, a prominent challenge associated with desalination is its high consumption of energy, which is often supplied largely by fossil fuels. However, newer and less energy-intensive plants are being developed, many of which are powered by renewable energy sources.
Different approaches can often complement each other. For example, by 2050 the countries in the Middle East and North Africa region are expected to meet 18 percent of their fresh water demand through increased efficiency gains, 14 percent through reuse of wastewater and 22 percent through solar powered desalination.
In the longer run, new technologies like Ocean Thermal Energy Conversion (OTEC) could also become viable. OTEC generates electricity from thermal energy in the oceans and produces plenty of fresh water in the process. OTEC is still untested on a large scale but is estimated to already be economically viable in island states if the fresh water produced is used. This promises a possible way around the so-called water-energy-(food) nexus, or the dilemma surrounding water and energy production wherein one often requires the other.