Water is the most essential requirement for all human activities such as drinking, agriculture and power generation. People would not survive without sufficient fresh water of good quality. Planet earth accommodates huge amounts of water, but only 1% is accessible as fresh water in lakes, rivers and aquifers (Jackson et al., 2001). The increasing human population over the last centuries has increased the pressure on this small fraction of accessible water. According to a report of the International Atomic Energy Agency (IAEA, 2011), two-thirds of the human population in 2025 will be confronted with water shortages and will not have access to save drinking water, even in regions where there is currently no water shortage.